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chromium / external / github.com / pwnall / sqlite / refs/heads/threads-closed / . / src / vdbesort.c
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/*
** 2011 July 9
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code for the VdbeSorter object, used in concert with
** a VdbeCursor to sort large numbers of keys (as may be required, for
** example, by CREATE INDEX statements on tables too large to fit in main
** memory).
*/
#include "sqliteInt.h"
#include "vdbeInt.h"
typedef struct VdbeSorterIter VdbeSorterIter;
typedef struct SorterThread SorterThread;
typedef struct SorterRecord SorterRecord;
typedef struct SorterMerger SorterMerger;
typedef struct FileWriter FileWriter;
/*
** Maximum number of threads to use. Setting this value to 1 forces all
** operations to be single-threaded.
*/
#ifndef SQLITE_MAX_SORTER_THREAD
# define SQLITE_MAX_SORTER_THREAD 4
#endif
/*
** Candidate values for SorterThread.eWork
*/
#define SORTER_THREAD_SORT 1
#define SORTER_THREAD_TO_PMA 2
#define SORTER_THREAD_CONS 3
/*
** Much of the work performed in this module to sort the list of records is
** broken down into smaller units that may be peformed in parallel. In order
** to perform such a unit of work, an instance of the following structure
** is configured and passed to vdbeSorterThreadMain() - either directly by
** the main thread or via a background thread.
**
** Exactly SQLITE_MAX_SORTER_THREAD instances of this structure are allocated
** as part of each VdbeSorter object. Instances are never allocated any other
** way.
**
** When a background thread is launched to perform work, SorterThread.bDone
** is set to 0 and the SorterThread.pThread variable set to point to the
** thread handle. SorterThread.bDone is set to 1 (to indicate to the main
** thread that joining SorterThread.pThread will not block) before the thread
** exits. SorterThread.pThread and bDone are always cleared after the
** background thread has been joined.
**
** One object (specifically, VdbeSorter.aThread[SQLITE_MAX_SORTER_THREAD-1])
** is reserved for the foreground thread.
**
** The nature of the work performed is determined by SorterThread.eWork,
** as follows:
**
** SORTER_THREAD_SORT:
** Sort the linked list of records at SorterThread.pList.
**
** SORTER_THREAD_TO_PMA:
** Sort the linked list of records at SorterThread.pList, and write
** the results to a new PMA in temp file SorterThread.pTemp1. Open
** the temp file if it is not already open.
**
** SORTER_THREAD_CONS:
** Merge existing PMAs until SorterThread.nConsolidate or fewer
** remain in temp file SorterThread.pTemp1.
*/
struct SorterThread {
SQLiteThread *pThread; /* Thread handle, or NULL */
int bDone; /* Set to true by pThread when finished */
sqlite3_vfs *pVfs; /* VFS used to open temporary files */
KeyInfo *pKeyInfo; /* How to compare records */
UnpackedRecord *pUnpacked; /* Space to unpack a record */
int pgsz; /* Main database page size */
u8 eWork; /* One of the SORTER_THREAD_* constants */
int nConsolidate; /* For THREAD_CONS, max final PMAs */
SorterRecord *pList; /* List of records for pThread to sort */
int nInMemory; /* Expected size of PMA based on pList */
u8 *aListMemory; /* Records memory (or NULL) */
u32 iSeq; /* Sequence number for PMA */
int nPMA; /* Number of PMAs currently in pTemp1 */
int bEmbeddedSeq; /* True if pTemp1 contains embedded seq. */
i64 iTemp1Off; /* Offset to write to in pTemp1 */
sqlite3_file *pTemp1; /* File to write PMAs to, or NULL */
};
/*
** NOTES ON DATA STRUCTURE USED FOR N-WAY MERGES:
**
** As keys are added to the sorter, they are written to disk in a series
** of sorted packed-memory-arrays (PMAs). The size of each PMA is roughly
** the same as the cache-size allowed for temporary databases. In order
** to allow the caller to extract keys from the sorter in sorted order,
** all PMAs currently stored on disk must be merged together. This comment
** describes the data structure used to do so. The structure supports
** merging any number of arrays in a single pass with no redundant comparison
** operations.
**
** The aIter[] array contains an iterator for each of the PMAs being merged.
** An aIter[] iterator either points to a valid key or else is at EOF. For
** the purposes of the paragraphs below, we assume that the array is actually
** N elements in size, where N is the smallest power of 2 greater to or equal
** to the number of iterators being merged. The extra aIter[] elements are
** treated as if they are empty (always at EOF).
**
** The aTree[] array is also N elements in size. The value of N is stored in
** the VdbeSorter.nTree variable.
**
** The final (N/2) elements of aTree[] contain the results of comparing
** pairs of iterator keys together. Element i contains the result of
** comparing aIter[2*i-N] and aIter[2*i-N+1]. Whichever key is smaller, the
** aTree element is set to the index of it.
**
** For the purposes of this comparison, EOF is considered greater than any
** other key value. If the keys are equal (only possible with two EOF
** values), it doesn't matter which index is stored.
**
** The (N/4) elements of aTree[] that precede the final (N/2) described
** above contains the index of the smallest of each block of 4 iterators.
** And so on. So that aTree[1] contains the index of the iterator that
** currently points to the smallest key value. aTree[0] is unused.
**
** Example:
**
** aIter[0] -> Banana
** aIter[1] -> Feijoa
** aIter[2] -> Elderberry
** aIter[3] -> Currant
** aIter[4] -> Grapefruit
** aIter[5] -> Apple
** aIter[6] -> Durian
** aIter[7] -> EOF
**
** aTree[] = { X, 5 0, 5 0, 3, 5, 6 }
**
** The current element is "Apple" (the value of the key indicated by
** iterator 5). When the Next() operation is invoked, iterator 5 will
** be advanced to the next key in its segment. Say the next key is
** "Eggplant":
**
** aIter[5] -> Eggplant
**
** The contents of aTree[] are updated first by comparing the new iterator
** 5 key to the current key of iterator 4 (still "Grapefruit"). The iterator
** 5 value is still smaller, so aTree[6] is set to 5. And so on up the tree.
** The value of iterator 6 - "Durian" - is now smaller than that of iterator
** 5, so aTree[3] is set to 6. Key 0 is smaller than key 6 (Banana<Durian),
** so the value written into element 1 of the array is 0. As follows:
**
** aTree[] = { X, 0 0, 6 0, 3, 5, 6 }
**
** In other words, each time we advance to the next sorter element, log2(N)
** key comparison operations are required, where N is the number of segments
** being merged (rounded up to the next power of 2).
*/
struct SorterMerger {
int nTree; /* Used size of aTree/aIter (power of 2) */
int *aTree; /* Current state of incremental merge */
VdbeSorterIter *aIter; /* Array of iterators to merge data from */
};
/*
** Main sorter structure. A single instance of this is allocated for each
** sorter cursor created by the VDBE.
*/
struct VdbeSorter {
int nInMemory; /* Current size of pRecord list as PMA */
int mnPmaSize; /* Minimum PMA size, in bytes */
int mxPmaSize; /* Maximum PMA size, in bytes. 0==no limit */
int bUsePMA; /* True if one or more PMAs created */
SorterRecord *pRecord; /* Head of in-memory record list */
SorterMerger *pMerger; /* For final merge of PMAs (by caller) */
u8 *aMemory; /* Block of memory to alloc records from */
int iMemory; /* Offset of first free byte in aMemory */
int nMemory; /* Size of aMemory allocation in bytes */
u32 iNextSeq; /* Sequence number for next PMA */
SorterThread aThread[SQLITE_MAX_SORTER_THREAD];
};
/*
** The following type is an iterator for a PMA. It caches the current key in
** variables nKey/aKey. If the iterator is at EOF, pFile==0.
*/
struct VdbeSorterIter {
i64 iReadOff; /* Current read offset */
i64 iEof; /* 1 byte past EOF for this iterator */
int bEmbeddedSeq; /* True if records have sequence values */
int iSeq; /* Current sequence value */
int nAlloc; /* Bytes of space at aAlloc */
int nKey; /* Number of bytes in key */
sqlite3_file *pFile; /* File iterator is reading from */
u8 *aAlloc; /* Allocated space */
u8 *aKey; /* Pointer to current key */
u8 *aBuffer; /* Current read buffer */
int nBuffer; /* Size of read buffer in bytes */
u8 *aMap; /* Pointer to mapping of entire file */
};
/*
** An instance of this structure is used to organize the stream of records
** being written to files by the merge-sort code into aligned, page-sized
** blocks. Doing all I/O in aligned page-sized blocks helps I/O to go
** faster on many operating systems.
*/
struct FileWriter {
int eFWErr; /* Non-zero if in an error state */
u8 *aBuffer; /* Pointer to write buffer */
int nBuffer; /* Size of write buffer in bytes */
int iBufStart; /* First byte of buffer to write */
int iBufEnd; /* Last byte of buffer to write */
i64 iWriteOff; /* Offset of start of buffer in file */
sqlite3_file *pFile; /* File to write to */
};
/*
** A structure to store a single record. All in-memory records are connected
** together into a linked list headed at VdbeSorter.pRecord.
**
** How the linked list is connected depends on how memory is being managed
** by this module. If using a separate allocation for each in-memory record
** (VdbeSorter.aMemory==0), then the list is always connected using the
** SorterRecord.u.pNext pointers.
**
** Or, if using the single large allocation method (VdbeSorter.aMemory!=0),
** then while records are being accumulated the list is linked using the
** SorterRecord.u.iNext offset. This is because the aMemory[] array may
** be sqlite3Realloc()ed while records are being accumulated. Once the VM
** has finished passing records to the sorter, or when the in-memory buffer
** is full, the list is sorted. As part of the sorting process, it is
** converted to use the SorterRecord.u.pNext pointers. See function
** vdbeSorterSort() for details.
*/
struct SorterRecord {
int nVal;
union {
SorterRecord *pNext; /* Pointer to next record in list */
int iNext; /* Offset within aMemory of next record */
} u;
};
/* Return a pointer to the buffer containing the record data for SorterRecord
** object p. Should be used as if:
**
** void *SRVAL(SorterRecord *p) { return (void*)&p[1]; }
*/
#define SRVAL(p) ((void*)((SorterRecord*)(p) + 1))
/* The minimum PMA size is set to this value multiplied by the database
** page size in bytes. */
#define SORTER_MIN_WORKING 10
/* Maximum number of segments to merge in a single pass. */
#define SORTER_MAX_MERGE_COUNT 16
/*
** Free all memory belonging to the VdbeSorterIter object passed as the second
** argument. All structure fields are set to zero before returning.
*/
static void vdbeSorterIterZero(VdbeSorterIter *pIter){
sqlite3_free(pIter->aAlloc);
sqlite3_free(pIter->aBuffer);
if( pIter->aMap ) sqlite3OsUnfetch(pIter->pFile, 0, pIter->aMap);
memset(pIter, 0, sizeof(VdbeSorterIter));
}
/*
** Read nByte bytes of data from the stream of data iterated by object p.
** If successful, set *ppOut to point to a buffer containing the data
** and return SQLITE_OK. Otherwise, if an error occurs, return an SQLite
** error code.
**
** The buffer indicated by *ppOut may only be considered valid until the
** next call to this function.
*/
static int vdbeSorterIterRead(
VdbeSorterIter *p, /* Iterator */
int nByte, /* Bytes of data to read */
u8 **ppOut /* OUT: Pointer to buffer containing data */
){
int iBuf; /* Offset within buffer to read from */
int nAvail; /* Bytes of data available in buffer */
if( p->aMap ){
*ppOut = &p->aMap[p->iReadOff];
p->iReadOff += nByte;
return SQLITE_OK;
}
assert( p->aBuffer );
/* If there is no more data to be read from the buffer, read the next
** p->nBuffer bytes of data from the file into it. Or, if there are less
** than p->nBuffer bytes remaining in the PMA, read all remaining data. */
iBuf = p->iReadOff % p->nBuffer;
if( iBuf==0 ){
int nRead; /* Bytes to read from disk */
int rc; /* sqlite3OsRead() return code */
/* Determine how many bytes of data to read. */
if( (p->iEof - p->iReadOff) > (i64)p->nBuffer ){
nRead = p->nBuffer;
}else{
nRead = (int)(p->iEof - p->iReadOff);
}
assert( nRead>0 );
/* Read data from the file. Return early if an error occurs. */
rc = sqlite3OsRead(p->pFile, p->aBuffer, nRead, p->iReadOff);
assert( rc!=SQLITE_IOERR_SHORT_READ );
if( rc!=SQLITE_OK ) return rc;
}
nAvail = p->nBuffer - iBuf;
if( nByte<=nAvail ){
/* The requested data is available in the in-memory buffer. In this
** case there is no need to make a copy of the data, just return a
** pointer into the buffer to the caller. */
*ppOut = &p->aBuffer[iBuf];
p->iReadOff += nByte;
}else{
/* The requested data is not all available in the in-memory buffer.
** In this case, allocate space at p->aAlloc[] to copy the requested
** range into. Then return a copy of pointer p->aAlloc to the caller. */
int nRem; /* Bytes remaining to copy */
/* Extend the p->aAlloc[] allocation if required. */
if( p->nAlloc<nByte ){
u8 *aNew;
int nNew = p->nAlloc*2;
while( nByte>nNew ) nNew = nNew*2;
aNew = sqlite3Realloc(p->aAlloc, nNew);
if( !aNew ) return SQLITE_NOMEM;
p->nAlloc = nNew;
p->aAlloc = aNew;
}
/* Copy as much data as is available in the buffer into the start of
** p->aAlloc[]. */
memcpy(p->aAlloc, &p->aBuffer[iBuf], nAvail);
p->iReadOff += nAvail;
nRem = nByte - nAvail;
/* The following loop copies up to p->nBuffer bytes per iteration into
** the p->aAlloc[] buffer. */
while( nRem>0 ){
int rc; /* vdbeSorterIterRead() return code */
int nCopy; /* Number of bytes to copy */
u8 *aNext; /* Pointer to buffer to copy data from */
nCopy = nRem;
if( nRem>p->nBuffer ) nCopy = p->nBuffer;
rc = vdbeSorterIterRead(p, nCopy, &aNext);
if( rc!=SQLITE_OK ) return rc;
assert( aNext!=p->aAlloc );
memcpy(&p->aAlloc[nByte - nRem], aNext, nCopy);
nRem -= nCopy;
}
*ppOut = p->aAlloc;
}
return SQLITE_OK;
}
/*
** Read a varint from the stream of data accessed by p. Set *pnOut to
** the value read.
*/
static int vdbeSorterIterVarint(VdbeSorterIter *p, u64 *pnOut){
int iBuf;
if( p->aMap ){
p->iReadOff += sqlite3GetVarint(&p->aMap[p->iReadOff], pnOut);
}else{
iBuf = p->iReadOff % p->nBuffer;
if( iBuf && (p->nBuffer-iBuf)>=9 ){
p->iReadOff += sqlite3GetVarint(&p->aBuffer[iBuf], pnOut);
}else{
u8 aVarint[16], *a;
int i = 0, rc;
do{
rc = vdbeSorterIterRead(p, 1, &a);
if( rc ) return rc;
aVarint[(i++)&0xf] = a[0];
}while( (a[0]&0x80)!=0 );
sqlite3GetVarint(aVarint, pnOut);
}
}
return SQLITE_OK;
}
/*
** Advance iterator pIter to the next key in its PMA. Return SQLITE_OK if
** no error occurs, or an SQLite error code if one does.
*/
static int vdbeSorterIterNext(VdbeSorterIter *pIter){
int rc; /* Return Code */
u64 nRec = 0; /* Size of record in bytes */
if( pIter->iReadOff>=pIter->iEof ){
/* This is an EOF condition */
vdbeSorterIterZero(pIter);
return SQLITE_OK;
}
rc = vdbeSorterIterVarint(pIter, &nRec);
if( rc==SQLITE_OK && pIter->bEmbeddedSeq ){
u64 iSeq;
rc = vdbeSorterIterVarint(pIter, &iSeq);
pIter->iSeq = (int)iSeq;
}
if( rc==SQLITE_OK ){
pIter->nKey = (int)nRec;
rc = vdbeSorterIterRead(pIter, (int)nRec, &pIter->aKey);
}
return rc;
}
/*
** Initialize iterator pIter to scan through the PMA stored in file pFile
** starting at offset iStart and ending at offset iEof-1. This function
** leaves the iterator pointing to the first key in the PMA (or EOF if the
** PMA is empty).
*/
static int vdbeSorterIterInit(
SorterThread *pThread, /* Thread context */
i64 iStart, /* Start offset in pThread->pTemp1 */
VdbeSorterIter *pIter, /* Iterator to populate */
i64 *pnByte /* IN/OUT: Increment this value by PMA size */
){
int rc = SQLITE_OK;
int nBuf = pThread->pgsz;
void *pMap = 0; /* Mapping of temp file */
assert( pThread->iTemp1Off>iStart );
assert( pIter->aAlloc==0 );
assert( pIter->aBuffer==0 );
pIter->pFile = pThread->pTemp1;
pIter->iReadOff = iStart;
pIter->nAlloc = 128;
pIter->aAlloc = (u8*)sqlite3Malloc(pIter->nAlloc);
pIter->bEmbeddedSeq = pThread->bEmbeddedSeq;
/* Try to xFetch() a mapping of the entire temp file. If this is possible,
** the PMA will be read via the mapping. Otherwise, use xRead(). */
rc = sqlite3OsFetch(pIter->pFile, 0, pThread->iTemp1Off, &pMap);
if( rc==SQLITE_OK ){
if( pMap ){
pIter->aMap = (u8*)pMap;
}else{
pIter->nBuffer = nBuf;
pIter->aBuffer = (u8*)sqlite3Malloc(nBuf);
if( !pIter->aBuffer ){
rc = SQLITE_NOMEM;
}else{
int iBuf = iStart % nBuf;
if( iBuf ){
int nRead = nBuf - iBuf;
if( (iStart + nRead) > pThread->iTemp1Off ){
nRead = (int)(pThread->iTemp1Off - iStart);
}
rc = sqlite3OsRead(
pThread->pTemp1, &pIter->aBuffer[iBuf], nRead, iStart
);
assert( rc!=SQLITE_IOERR_SHORT_READ );
}
}
}
}
if( rc==SQLITE_OK ){
u64 nByte; /* Size of PMA in bytes */
pIter->iEof = pThread->iTemp1Off;
if( pIter->bEmbeddedSeq==0 ){
u64 iSeq, nElem;
rc = vdbeSorterIterVarint(pIter, &iSeq);
pIter->iSeq = (int)iSeq;
if( rc==SQLITE_OK ){
rc = vdbeSorterIterVarint(pIter, &nElem);
*pnByte += (nElem * sqlite3VarintLen(iSeq));
}
}
if( rc==SQLITE_OK ){
rc = vdbeSorterIterVarint(pIter, &nByte);
pIter->iEof = pIter->iReadOff + nByte;
*pnByte += nByte;
}
}
if( rc==SQLITE_OK ){
rc = vdbeSorterIterNext(pIter);
}
return rc;
}
/*
** Compare key1 (buffer pKey1, size nKey1 bytes) with key2 (buffer pKey2,
** size nKey2 bytes). Argument pKeyInfo supplies the collation functions
** used by the comparison. If an error occurs, return an SQLite error code.
** Otherwise, return SQLITE_OK and set *pRes to a negative, zero or positive
** value, depending on whether key1 is smaller, equal to or larger than key2.
**
** If the bOmitRowid argument is non-zero, assume both keys end in a rowid
** field. For the purposes of the comparison, ignore it. Also, if bOmitRowid
** is true and key1 contains even a single NULL value, it is considered to
** be less than key2. Even if key2 also contains NULL values.
**
** If pKey2 is passed a NULL pointer, then it is assumed that the pCsr->aSpace
** has been allocated and contains an unpacked record that is used as key2.
*/
static void vdbeSorterCompare(
SorterThread *pThread, /* Thread context (for pKeyInfo) */
int nIgnore, /* Ignore the last nIgnore fields */
const void *pKey1, int nKey1, /* Left side of comparison */
const void *pKey2, int nKey2, /* Right side of comparison */
int *pRes /* OUT: Result of comparison */
){
KeyInfo *pKeyInfo = pThread->pKeyInfo;
UnpackedRecord *r2 = pThread->pUnpacked;
int i;
if( pKey2 ){
sqlite3VdbeRecordUnpack(pKeyInfo, nKey2, pKey2, r2);
}
if( nIgnore ){
r2->nField = pKeyInfo->nField - nIgnore;
assert( r2->nField>0 );
for(i=0; i<r2->nField; i++){
if( r2->aMem[i].flags & MEM_Null ){
*pRes = -1;
return;
}
}
assert( r2->default_rc==0 );
}
*pRes = sqlite3VdbeRecordCompare(nKey1, pKey1, r2, 0);
}
/*
** This function is called to compare two iterator keys when merging
** multiple b-tree segments. Parameter iOut is the index of the aTree[]
** value to recalculate.
*/
static int vdbeSorterDoCompare(
SorterThread *pThread,
SorterMerger *pMerger,
int iOut
){
int i1;
int i2;
int iRes;
VdbeSorterIter *p1;
VdbeSorterIter *p2;
assert( iOut<pMerger->nTree && iOut>0 );
if( iOut>=(pMerger->nTree/2) ){
i1 = (iOut - pMerger->nTree/2) * 2;
i2 = i1 + 1;
}else{
i1 = pMerger->aTree[iOut*2];
i2 = pMerger->aTree[iOut*2+1];
}
p1 = &pMerger->aIter[i1];
p2 = &pMerger->aIter[i2];
if( p1->pFile==0 ){
iRes = i2;
}else if( p2->pFile==0 ){
iRes = i1;
}else{
int res;
assert( pThread->pUnpacked!=0 ); /* allocated in vdbeSorterMerge() */
vdbeSorterCompare(
pThread, 0, p1->aKey, p1->nKey, p2->aKey, p2->nKey, &res
);
if( res<=0 ){
iRes = i1;
}else{
iRes = i2;
}
}
pMerger->aTree[iOut] = iRes;
return SQLITE_OK;
}
/*
** Initialize the temporary index cursor just opened as a sorter cursor.
*/
int sqlite3VdbeSorterInit(sqlite3 *db, VdbeCursor *pCsr){
int pgsz; /* Page size of main database */
int i; /* Used to iterate through aThread[] */
int mxCache; /* Cache size */
VdbeSorter *pSorter; /* The new sorter */
KeyInfo *pKeyInfo; /* Copy of pCsr->pKeyInfo with db==0 */
int szKeyInfo; /* Size of pCsr->pKeyInfo in bytes */
int rc = SQLITE_OK;
assert( pCsr->pKeyInfo && pCsr->pBt==0 );
szKeyInfo = sizeof(KeyInfo) + (pCsr->pKeyInfo->nField-1)*sizeof(CollSeq*);
pSorter = (VdbeSorter*)sqlite3DbMallocZero(db, sizeof(VdbeSorter)+szKeyInfo);
pCsr->pSorter = pSorter;
if( pSorter==0 ){
rc = SQLITE_NOMEM;
}else{
pKeyInfo = (KeyInfo*)&pSorter[1];
memcpy(pKeyInfo, pCsr->pKeyInfo, szKeyInfo);
pKeyInfo->db = 0;
pgsz = sqlite3BtreeGetPageSize(db->aDb[0].pBt);
for(i=0; i<SQLITE_MAX_SORTER_THREAD; i++){
SorterThread *pThread = &pSorter->aThread[i];
pThread->pKeyInfo = pKeyInfo;
pThread->pVfs = db->pVfs;
pThread->pgsz = pgsz;
}
if( !sqlite3TempInMemory(db) ){
pSorter->mnPmaSize = SORTER_MIN_WORKING * pgsz;
mxCache = db->aDb[0].pSchema->cache_size;
if( mxCache<SORTER_MIN_WORKING ) mxCache = SORTER_MIN_WORKING;
pSorter->mxPmaSize = mxCache * pgsz;
/* If the application is using memsys3 or memsys5, use a separate
** allocation for each sort-key in memory. Otherwise, use a single big
** allocation at pSorter->aMemory for all sort-keys. */
if( sqlite3GlobalConfig.pHeap==0 ){
assert( pSorter->iMemory==0 );
pSorter->nMemory = pgsz;
pSorter->aMemory = (u8*)sqlite3Malloc(pgsz);
if( !pSorter->aMemory ) rc = SQLITE_NOMEM;
}
}
}
return rc;
}
/*
** Free the list of sorted records starting at pRecord.
*/
static void vdbeSorterRecordFree(sqlite3 *db, SorterRecord *pRecord){
SorterRecord *p;
SorterRecord *pNext;
for(p=pRecord; p; p=pNext){
pNext = p->u.pNext;
sqlite3DbFree(db, p);
}
}
/*
** Free all resources owned by the object indicated by argument pThread. All
** fields of *pThread are zeroed before returning.
*/
static void vdbeSorterThreadCleanup(sqlite3 *db, SorterThread *pThread){
sqlite3DbFree(db, pThread->pUnpacked);
pThread->pUnpacked = 0;
if( pThread->aListMemory==0 ){
vdbeSorterRecordFree(0, pThread->pList);
}else{
sqlite3_free(pThread->aListMemory);
pThread->aListMemory = 0;
}
pThread->pList = 0;
if( pThread->pTemp1 ){
sqlite3OsCloseFree(pThread->pTemp1);
pThread->pTemp1 = 0;
}
}
/*
** Join all threads.
*/
static int vdbeSorterJoinAll(VdbeSorter *pSorter, int rcin){
int rc = rcin;
int i;
for(i=0; i<SQLITE_MAX_SORTER_THREAD; i++){
SorterThread *pThread = &pSorter->aThread[i];
if( pThread->pThread ){
void *pRet;
int rc2 = sqlite3ThreadJoin(pThread->pThread, &pRet);
pThread->pThread = 0;
pThread->bDone = 0;
if( rc==SQLITE_OK ) rc = rc2;
if( rc==SQLITE_OK ) rc = SQLITE_PTR_TO_INT(pRet);
}
}
return rc;
}
/*
** Allocate a new SorterMerger object with space for nIter iterators.
*/
static SorterMerger *vdbeSorterMergerNew(int nIter){
int N = 2; /* Smallest power of two >= nIter */
int nByte; /* Total bytes of space to allocate */
SorterMerger *pNew; /* Pointer to allocated object to return */
assert( nIter<=SORTER_MAX_MERGE_COUNT );
while( N<nIter ) N += N;
nByte = sizeof(SorterMerger) + N * (sizeof(int) + sizeof(VdbeSorterIter));
pNew = (SorterMerger*)sqlite3MallocZero(nByte);
if( pNew ){
pNew->nTree = N;
pNew->aIter = (VdbeSorterIter*)&pNew[1];
pNew->aTree = (int*)&pNew->aIter[N];
}
return pNew;
}
/*
** Reset a merger
*/
static void vdbeSorterMergerReset(SorterMerger *pMerger){
int i;
if( pMerger ){
for(i=0; i<pMerger->nTree; i++){
vdbeSorterIterZero(&pMerger->aIter[i]);
}
}
}
/*
** Free the SorterMerger object passed as the only argument.
*/
static void vdbeSorterMergerFree(SorterMerger *pMerger){
vdbeSorterMergerReset(pMerger);
sqlite3_free(pMerger);
}
/*
** Reset a sorting cursor back to its original empty state.
*/
void sqlite3VdbeSorterReset(sqlite3 *db, VdbeSorter *pSorter){
int i;
vdbeSorterJoinAll(pSorter, SQLITE_OK);
for(i=0; i<SQLITE_MAX_SORTER_THREAD; i++){
SorterThread *pThread = &pSorter->aThread[i];
vdbeSorterThreadCleanup(db, pThread);
}
if( pSorter->aMemory==0 ){
vdbeSorterRecordFree(0, pSorter->pRecord);
}
vdbeSorterMergerReset(pSorter->pMerger);
pSorter->pRecord = 0;
pSorter->nInMemory = 0;
pSorter->bUsePMA = 0;
pSorter->iMemory = 0;
pSorter->iNextSeq = 0;
}
/*
** Free any cursor components allocated by sqlite3VdbeSorterXXX routines.
*/
void sqlite3VdbeSorterClose(sqlite3 *db, VdbeCursor *pCsr){
VdbeSorter *pSorter = pCsr->pSorter;
if( pSorter ){
sqlite3VdbeSorterReset(db, pSorter);
vdbeSorterMergerFree(pSorter->pMerger);
sqlite3_free(pSorter->aMemory);
sqlite3DbFree(db, pSorter);
pCsr->pSorter = 0;
}
}
/*
** Allocate space for a file-handle and open a temporary file. If successful,
** set *ppFile to point to the malloc'd file-handle and return SQLITE_OK.
** Otherwise, set *ppFile to 0 and return an SQLite error code.
*/
static int vdbeSorterOpenTempFile(sqlite3_vfs *pVfs, sqlite3_file **ppFile){
int rc;
rc = sqlite3OsOpenMalloc(pVfs, 0, ppFile,
SQLITE_OPEN_TEMP_JOURNAL |
SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE |
SQLITE_OPEN_EXCLUSIVE | SQLITE_OPEN_DELETEONCLOSE, &rc
);
if( rc==SQLITE_OK ){
i64 max = SQLITE_MAX_MMAP_SIZE;
sqlite3OsFileControlHint( *ppFile, SQLITE_FCNTL_MMAP_SIZE, (void*)&max);
}
return rc;
}
/*
** Merge the two sorted lists p1 and p2 into a single list.
** Set *ppOut to the head of the new list.
*/
static void vdbeSorterMerge(
SorterThread *pThread, /* Calling thread context */
SorterRecord *p1, /* First list to merge */
SorterRecord *p2, /* Second list to merge */
SorterRecord **ppOut /* OUT: Head of merged list */
){
SorterRecord *pFinal = 0;
SorterRecord **pp = &pFinal;
void *pVal2 = p2 ? SRVAL(p2) : 0;
while( p1 && p2 ){
int res;
vdbeSorterCompare(pThread, 0, SRVAL(p1), p1->nVal, pVal2, p2->nVal, &res);
if( res<=0 ){
*pp = p1;
pp = &p1->u.pNext;
p1 = p1->u.pNext;
pVal2 = 0;
}else{
*pp = p2;
pp = &p2->u.pNext;
p2 = p2->u.pNext;
if( p2==0 ) break;
pVal2 = SRVAL(p2);
}
}
*pp = p1 ? p1 : p2;
*ppOut = pFinal;
}
/*
** Sort the linked list of records headed at pThread->pList. Return
** SQLITE_OK if successful, or an SQLite error code (i.e. SQLITE_NOMEM) if
** an error occurs.
**
** If the pnElem argument is not NULL and no error occurs, set *pnElem to
** the total number of elements in the list.
*/
static int vdbeSorterSort(SorterThread *pThread, i64 *pnElem){
int i;
SorterRecord **aSlot;
SorterRecord *p;
i64 nElem = 0;
aSlot = (SorterRecord **)sqlite3MallocZero(64 * sizeof(SorterRecord *));
if( !aSlot ){
return SQLITE_NOMEM;
}
p = pThread->pList;
while( p ){
SorterRecord *pNext;
if( pThread->aListMemory ){
if( (u8*)p==pThread->aListMemory ){
pNext = 0;
}else{
assert( p->u.iNext<sqlite3MallocSize(pThread->aListMemory) );
pNext = (SorterRecord*)&pThread->aListMemory[p->u.iNext];
}
}else{
pNext = p->u.pNext;
}
p->u.pNext = 0;
for(i=0; aSlot[i]; i++){
vdbeSorterMerge(pThread, p, aSlot[i], &p);
aSlot[i] = 0;
}
aSlot[i] = p;
p = pNext;
nElem++;
}
p = 0;
for(i=0; i<64; i++){
vdbeSorterMerge(pThread, p, aSlot[i], &p);
}
pThread->pList = p;
*pnElem = nElem;
sqlite3_free(aSlot);
return SQLITE_OK;
}
/*
** Initialize a file-writer object.
*/
static void fileWriterInit(
sqlite3_file *pFile, /* File to write to */
FileWriter *p, /* Object to populate */
int nBuf, /* Buffer size */
i64 iStart /* Offset of pFile to begin writing at */
){
memset(p, 0, sizeof(FileWriter));
p->aBuffer = (u8*)sqlite3Malloc(nBuf);
if( !p->aBuffer ){
p->eFWErr = SQLITE_NOMEM;
}else{
p->iBufEnd = p->iBufStart = (iStart % nBuf);
p->iWriteOff = iStart - p->iBufStart;
p->nBuffer = nBuf;
p->pFile = pFile;
}
}
/*
** Write nData bytes of data to the file-write object. Return SQLITE_OK
** if successful, or an SQLite error code if an error occurs.
*/
static void fileWriterWrite(FileWriter *p, u8 *pData, int nData){
int nRem = nData;
while( nRem>0 && p->eFWErr==0 ){
int nCopy = nRem;
if( nCopy>(p->nBuffer - p->iBufEnd) ){
nCopy = p->nBuffer - p->iBufEnd;
}
memcpy(&p->aBuffer[p->iBufEnd], &pData[nData-nRem], nCopy);
p->iBufEnd += nCopy;
if( p->iBufEnd==p->nBuffer ){
p->eFWErr = sqlite3OsWrite(p->pFile,
&p->aBuffer[p->iBufStart], p->iBufEnd - p->iBufStart,
p->iWriteOff + p->iBufStart
);
p->iBufStart = p->iBufEnd = 0;
p->iWriteOff += p->nBuffer;
}
assert( p->iBufEnd<p->nBuffer );
nRem -= nCopy;
}
}
/*
** Flush any buffered data to disk and clean up the file-writer object.
** The results of using the file-writer after this call are undefined.
** Return SQLITE_OK if flushing the buffered data succeeds or is not
** required. Otherwise, return an SQLite error code.
**
** Before returning, set *piEof to the offset immediately following the
** last byte written to the file.
*/
static int fileWriterFinish(FileWriter *p, i64 *piEof){
int rc;
if( p->eFWErr==0 && ALWAYS(p->aBuffer) && p->iBufEnd>p->iBufStart ){
p->eFWErr = sqlite3OsWrite(p->pFile,
&p->aBuffer[p->iBufStart], p->iBufEnd - p->iBufStart,
p->iWriteOff + p->iBufStart
);
}
*piEof = (p->iWriteOff + p->iBufEnd);
sqlite3_free(p->aBuffer);
rc = p->eFWErr;
memset(p, 0, sizeof(FileWriter));
return rc;
}
/*
** Write value iVal encoded as a varint to the file-write object. Return
** SQLITE_OK if successful, or an SQLite error code if an error occurs.
*/
static void fileWriterWriteVarint(FileWriter *p, u64 iVal){
int nByte;
u8 aByte[10];
nByte = sqlite3PutVarint(aByte, iVal);
fileWriterWrite(p, aByte, nByte);
}
#if SQLITE_MAX_MMAP_SIZE>0
/*
** The first argument is a file-handle open on a temporary file. The file
** is guaranteed to be nByte bytes or smaller in size. This function
** attempts to extend the file to nByte bytes in size and to ensure that
** the VFS has memory mapped it.
**
** Whether or not the file does end up memory mapped of course depends on
** the specific VFS implementation.
*/
static int vdbeSorterExtendFile(sqlite3_file *pFile, i64 nByte){
int rc = sqlite3OsTruncate(pFile, nByte);
if( rc==SQLITE_OK ){
void *p = 0;
sqlite3OsFetch(pFile, 0, nByte, &p);
sqlite3OsUnfetch(pFile, 0, p);
}
return rc;
}
#else
# define vdbeSorterExtendFile(x,y) SQLITE_OK
#endif
/*
** Write the current contents of the in-memory linked-list to a PMA. Return
** SQLITE_OK if successful, or an SQLite error code otherwise.
**
** The format of a PMA is:
**
** * A varint. This varint contains the total number of bytes of content
** in the PMA (not including the varint itself).
**
** * One or more records packed end-to-end in order of ascending keys.
** Each record consists of a varint followed by a blob of data (the
** key). The varint is the number of bytes in the blob of data.
*/
static int vdbeSorterListToPMA(SorterThread *pThread, i64 nElem){
int rc = SQLITE_OK; /* Return code */
FileWriter writer; /* Object used to write to the file */
memset(&writer, 0, sizeof(FileWriter));
assert( pThread->nInMemory>0 );
/* If the first temporary PMA file has not been opened, open it now. */
if( pThread->pTemp1==0 ){
rc = vdbeSorterOpenTempFile(pThread->pVfs, &pThread->pTemp1);
assert( rc!=SQLITE_OK || pThread->pTemp1 );
assert( pThread->iTemp1Off==0 );
assert( pThread->nPMA==0 );
assert( pThread->bEmbeddedSeq==0 );
}
/* Try to get the file to memory map */
if( rc==SQLITE_OK ){
rc = vdbeSorterExtendFile(
pThread->pTemp1, pThread->iTemp1Off + 9 + 9 + 9 + pThread->nInMemory
);
}
if( rc==SQLITE_OK ){
SorterRecord *p;
SorterRecord *pNext = 0;
fileWriterInit(pThread->pTemp1, &writer, pThread->pgsz, pThread->iTemp1Off);
pThread->nPMA++;
fileWriterWriteVarint(&writer, (u64)pThread->iSeq);
fileWriterWriteVarint(&writer, (u64)nElem);
fileWriterWriteVarint(&writer, pThread->nInMemory);
for(p=pThread->pList; p; p=pNext){
pNext = p->u.pNext;
fileWriterWriteVarint(&writer, p->nVal);
fileWriterWrite(&writer, SRVAL(p), p->nVal);
if( pThread->aListMemory==0 ) sqlite3_free(p);
}
pThread->pList = p;
rc = fileWriterFinish(&writer, &pThread->iTemp1Off);
}
assert( pThread->pList==0 || rc!=SQLITE_OK );
return rc;
}
/*
** Advance the SorterMerger iterator passed as the second argument to
** the next entry. Set *pbEof to true if this means the iterator has
** reached EOF.
**
** Return SQLITE_OK if successful or an error code if an error occurs.
*/
static int vdbeSorterNext(
SorterThread *pThread,
SorterMerger *pMerger,
int *pbEof
){
int rc;
int iPrev = pMerger->aTree[1];/* Index of iterator to advance */
/* Advance the current iterator */
rc = vdbeSorterIterNext(&pMerger->aIter[iPrev]);
/* Update contents of aTree[] */
if( rc==SQLITE_OK ){
int i; /* Index of aTree[] to recalculate */
VdbeSorterIter *pIter1; /* First iterator to compare */
VdbeSorterIter *pIter2; /* Second iterator to compare */
u8 *pKey2; /* To pIter2->aKey, or 0 if record cached */
/* Find the first two iterators to compare. The one that was just
** advanced (iPrev) and the one next to it in the array. */
pIter1 = &pMerger->aIter[(iPrev & 0xFFFE)];
pIter2 = &pMerger->aIter[(iPrev | 0x0001)];
pKey2 = pIter2->aKey;
for(i=(pMerger->nTree+iPrev)/2; i>0; i=i/2){
/* Compare pIter1 and pIter2. Store the result in variable iRes. */
int iRes;
if( pIter1->pFile==0 ){
iRes = +1;
}else if( pIter2->pFile==0 ){
iRes = -1;
}else{
vdbeSorterCompare(pThread, 0,
pIter1->aKey, pIter1->nKey, pKey2, pIter2->nKey, &iRes
);
}
/* If pIter1 contained the smaller value, set aTree[i] to its index.
** Then set pIter2 to the next iterator to compare to pIter1. In this
** case there is no cache of pIter2 in pThread->pUnpacked, so set
** pKey2 to point to the record belonging to pIter2.
**
** Alternatively, if pIter2 contains the smaller of the two values,
** set aTree[i] to its index and update pIter1. If vdbeSorterCompare()
** was actually called above, then pThread->pUnpacked now contains
** a value equivalent to pIter2. So set pKey2 to NULL to prevent
** vdbeSorterCompare() from decoding pIter2 again.
**
** If the two values were equal, then the value from the oldest
** PMA should be considered smaller. The VdbeSorter.aIter[] array
** is sorted from oldest to newest, so pIter1 contains older values
** than pIter2 iff (pIter1<pIter2). */
if( iRes<0 || (iRes==0 && pIter1->iSeq < pIter2->iSeq) ){
pMerger->aTree[i] = (int)(pIter1 - pMerger->aIter);
pIter2 = &pMerger->aIter[ pMerger->aTree[i ^ 0x0001] ];
pKey2 = pIter2->aKey;
}else{
if( pIter1->pFile ) pKey2 = 0;
pMerger->aTree[i] = (int)(pIter2 - pMerger->aIter);
pIter1 = &pMerger->aIter[ pMerger->aTree[i ^ 0x0001] ];
}
}
*pbEof = (pMerger->aIter[pMerger->aTree[1]].pFile==0);
}
return rc;
}
/*
** The main routine for sorter-thread operations.
*/
static void *vdbeSorterThreadMain(void *pCtx){
int rc = SQLITE_OK;
SorterThread *pThread = (SorterThread*)pCtx;
assert( pThread->eWork==SORTER_THREAD_SORT
|| pThread->eWork==SORTER_THREAD_TO_PMA
|| pThread->eWork==SORTER_THREAD_CONS
);
assert( pThread->bDone==0 );
if( pThread->pUnpacked==0 ){
char *pFree;
pThread->pUnpacked = sqlite3VdbeAllocUnpackedRecord(
pThread->pKeyInfo, 0, 0, &pFree
);
assert( pThread->pUnpacked==(UnpackedRecord*)pFree );
if( pFree==0 ){
rc = SQLITE_NOMEM;
goto thread_out;
}
pThread->pUnpacked->nField = pThread->pKeyInfo->nField;
}
if( pThread->eWork==SORTER_THREAD_CONS ){
assert( pThread->pList==0 );
while( pThread->nPMA>pThread->nConsolidate && rc==SQLITE_OK ){
int nIter = MIN(pThread->nPMA, SORTER_MAX_MERGE_COUNT);
sqlite3_file *pTemp2 = 0; /* Second temp file to use */
SorterMerger *pMerger; /* Object for reading/merging PMA data */
i64 iReadOff = 0; /* Offset in pTemp1 to read from */
i64 iWriteOff = 0; /* Offset in pTemp2 to write to */
int i;
/* Allocate a merger object to merge PMAs together. */
pMerger = vdbeSorterMergerNew(nIter);
if( pMerger==0 ){
rc = SQLITE_NOMEM;
break;
}
/* Open a second temp file to write merged data to */
rc = vdbeSorterOpenTempFile(pThread->pVfs, &pTemp2);
if( rc==SQLITE_OK ){
rc = vdbeSorterExtendFile(pTemp2, pThread->iTemp1Off);
}
if( rc!=SQLITE_OK ){
vdbeSorterMergerFree(pMerger);
break;
}
/* This loop runs once for each output PMA. Each output PMA is made
** of data merged from up to SORTER_MAX_MERGE_COUNT input PMAs. */
for(i=0; i<pThread->nPMA; i+=SORTER_MAX_MERGE_COUNT){
FileWriter writer; /* Object for writing data to pTemp2 */
i64 nOut = 0; /* Bytes of data in output PMA */
int bEof = 0;
int rc2;
/* Configure the merger object to read and merge data from the next
** SORTER_MAX_MERGE_COUNT PMAs in pTemp1 (or from all remaining PMAs,
** if that is fewer). */
int iIter;
for(iIter=0; iIter<SORTER_MAX_MERGE_COUNT; iIter++){
VdbeSorterIter *pIter = &pMerger->aIter[iIter];
rc = vdbeSorterIterInit(pThread, iReadOff, pIter, &nOut);
iReadOff = pIter->iEof;
if( iReadOff>=pThread->iTemp1Off || rc!=SQLITE_OK ) break;
}
for(iIter=pMerger->nTree-1; rc==SQLITE_OK && iIter>0; iIter--){
rc = vdbeSorterDoCompare(pThread, pMerger, iIter);
}
fileWriterInit(pTemp2, &writer, pThread->pgsz, iWriteOff);
fileWriterWriteVarint(&writer, nOut);
while( rc==SQLITE_OK && bEof==0 ){
VdbeSorterIter *pIter = &pMerger->aIter[ pMerger->aTree[1] ];
assert( pIter->pFile!=0 ); /* pIter is not at EOF */
fileWriterWriteVarint(&writer, pIter->nKey);
fileWriterWriteVarint(&writer, (u64)pIter->iSeq);
fileWriterWrite(&writer, pIter->aKey, pIter->nKey);
rc = vdbeSorterNext(pThread, pMerger, &bEof);
}
rc2 = fileWriterFinish(&writer, &iWriteOff);
if( rc==SQLITE_OK ) rc = rc2;
}
vdbeSorterMergerFree(pMerger);
sqlite3OsCloseFree(pThread->pTemp1);
pThread->pTemp1 = pTemp2;
pThread->nPMA = (i / SORTER_MAX_MERGE_COUNT);
pThread->iTemp1Off = iWriteOff;
pThread->bEmbeddedSeq = 1;
sqlite3OsUnfetch(pTemp2, 0, 0);
}
}else{
i64 nElem;
/* Sort the pThread->pList list */
rc = vdbeSorterSort(pThread, &nElem);
/* If required, write the list out to a PMA. */
if( rc==SQLITE_OK && pThread->eWork==SORTER_THREAD_TO_PMA ){
#ifdef SQLITE_DEBUG
i64 nExpect = pThread->nInMemory
+ sqlite3VarintLen(pThread->nInMemory)
+ sqlite3VarintLen(pThread->iSeq)
+ sqlite3VarintLen(nElem)
+ pThread->iTemp1Off;
#endif
rc = vdbeSorterListToPMA(pThread, nElem);
assert( rc!=SQLITE_OK || (nExpect==pThread->iTemp1Off) );
}
}
thread_out:
pThread->bDone = 1;
return SQLITE_INT_TO_PTR(rc);
}
/*
** Run the activity scheduled by the object passed as the only argument
** in the current thread.
*/
static int vdbeSorterRunThread(SorterThread *pThread){
int rc = SQLITE_PTR_TO_INT( vdbeSorterThreadMain((void*)pThread) );
assert( pThread->bDone );
pThread->bDone = 0;
return rc;
}
/*
** Flush the current contents of VdbeSorter.pRecord to a new PMA, possibly
** using a background thread.
**
** If argument bFg is non-zero, the operation always uses the calling thread.
*/
static int vdbeSorterFlushPMA(sqlite3 *db, const VdbeCursor *pCsr, int bFg){
VdbeSorter *pSorter = pCsr->pSorter;
int rc = SQLITE_OK;
int i;
SorterThread *pThread; /* Thread context used to create new PMA */
pSorter->bUsePMA = 1;
for(i=0; ALWAYS( i<SQLITE_MAX_SORTER_THREAD ); i++){
pThread = &pSorter->aThread[i];
if( pThread->bDone ){
void *pRet;
assert( pThread->pThread );
rc = sqlite3ThreadJoin(pThread->pThread, &pRet);
pThread->pThread = 0;
pThread->bDone = 0;
if( rc==SQLITE_OK ){
rc = SQLITE_PTR_TO_INT(pRet);
}
}
if( pThread->pThread==0 ) break;
}
if( rc==SQLITE_OK ){
int bUseFg = (bFg || i==(SQLITE_MAX_SORTER_THREAD-1));
assert( pThread->pThread==0 && pThread->bDone==0 );
pThread->eWork = SORTER_THREAD_TO_PMA;
pThread->pList = pSorter->pRecord;
pThread->nInMemory = pSorter->nInMemory;
pThread->iSeq = pSorter->iNextSeq++;
pSorter->nInMemory = 0;
pSorter->pRecord = 0;
if( pSorter->aMemory ){
u8 *aMem = pThread->aListMemory;
pThread->aListMemory = pSorter->aMemory;
pSorter->aMemory = aMem;
}
if( bUseFg==0 ){
/* Launch a background thread for this operation */
void *pCtx = (void*)pThread;
assert( pSorter->aMemory==0 || pThread->aListMemory!=0 );
if( pThread->aListMemory ){
if( pSorter->aMemory==0 ){
pSorter->aMemory = sqlite3Malloc(pSorter->nMemory);
if( pSorter->aMemory==0 ) return SQLITE_NOMEM;
}else{
pSorter->nMemory = sqlite3MallocSize(pSorter->aMemory);
}
}
rc = sqlite3ThreadCreate(&pThread->pThread, vdbeSorterThreadMain, pCtx);
}else{
/* Use the foreground thread for this operation */
u8 *aMem;
rc = vdbeSorterRunThread(pThread);
aMem = pThread->aListMemory;
pThread->aListMemory = pSorter->aMemory;
pSorter->aMemory = aMem;
}
}
return rc;
}
/*
** Add a record to the sorter.
*/
int sqlite3VdbeSorterWrite(
sqlite3 *db, /* Database handle */
const VdbeCursor *pCsr, /* Sorter cursor */
Mem *pVal /* Memory cell containing record */
){
VdbeSorter *pSorter = pCsr->pSorter;
int rc = SQLITE_OK; /* Return Code */
SorterRecord *pNew; /* New list element */
int bFlush; /* True to flush contents of memory to PMA */
int nReq; /* Bytes of memory required */
int nPMA; /* Bytes of PMA space required */
assert( pSorter );
/* Figure out whether or not the current contents of memory should be
** flushed to a PMA before continuing. If so, do so.
**
** If using the single large allocation mode (pSorter->aMemory!=0), then
** flush the contents of memory to a new PMA if (a) at least one value is
** already in memory and (b) the new value will not fit in memory.
**
** Or, if using separate allocations for each record, flush the contents
** of memory to a PMA if either of the following are true:
**
** * The total memory allocated for the in-memory list is greater
** than (page-size * cache-size), or
**
** * The total memory allocated for the in-memory list is greater
** than (page-size * 10) and sqlite3HeapNearlyFull() returns true.
*/
nReq = pVal->n + sizeof(SorterRecord);
nPMA = pVal->n + sqlite3VarintLen(pVal->n);
if( pSorter->mxPmaSize ){
if( pSorter->aMemory ){
bFlush = pSorter->iMemory && (pSorter->iMemory+nReq) > pSorter->mxPmaSize;
}else{
bFlush = (
(pSorter->nInMemory > pSorter->mxPmaSize)
|| (pSorter->nInMemory > pSorter->mnPmaSize && sqlite3HeapNearlyFull())
);
}
if( bFlush ){
rc = vdbeSorterFlushPMA(db, pCsr, 0);
pSorter->nInMemory = 0;
pSorter->iMemory = 0;
assert( rc!=SQLITE_OK || pSorter->pRecord==0 );
}
}
pSorter->nInMemory += nPMA;
if( pSorter->aMemory ){
int nMin = pSorter->iMemory + nReq;
if( nMin>pSorter->nMemory ){
u8 *aNew;
int nNew = pSorter->nMemory * 2;
while( nNew < nMin ) nNew = nNew*2;
if( nNew > pSorter->mxPmaSize ) nNew = pSorter->mxPmaSize;
if( nNew < nMin ) nNew = nMin;
aNew = sqlite3Realloc(pSorter->aMemory, nNew);
if( !aNew ) return SQLITE_NOMEM;
pSorter->pRecord = aNew + ((u8*)pSorter->pRecord - pSorter->aMemory);
pSorter->aMemory = aNew;
pSorter->nMemory = nNew;
}
pNew = (SorterRecord*)&pSorter->aMemory[pSorter->iMemory];
pSorter->iMemory += ROUND8(nReq);
pNew->u.iNext = (u8*)(pSorter->pRecord) - pSorter->aMemory;
}else{
pNew = (SorterRecord *)sqlite3Malloc(nReq);
if( pNew==0 ){
return SQLITE_NOMEM;
}
pNew->u.pNext = pSorter->pRecord;
}
memcpy(SRVAL(pNew), pVal->z, pVal->n);
pNew->nVal = pVal->n;
pSorter->pRecord = pNew;
return rc;
}
/*
** Return the total number of PMAs in all temporary files.
*/
static int vdbeSorterCountPMA(VdbeSorter *pSorter){
int nPMA = 0;
int i;
for(i=0; i<SQLITE_MAX_SORTER_THREAD; i++){
nPMA += pSorter->aThread[i].nPMA;
}
return nPMA;
}
/*
** Once the sorter has been populated, this function is called to prepare
** for iterating through its contents in sorted order.
*/
int sqlite3VdbeSorterRewind(sqlite3 *db, const VdbeCursor *pCsr, int *pbEof){
VdbeSorter *pSorter = pCsr->pSorter;
int rc = SQLITE_OK; /* Return code */
assert( pSorter );
/* If no data has been written to disk, then do not do so now. Instead,
** sort the VdbeSorter.pRecord list. The vdbe layer will read data directly
** from the in-memory list. */
if( pSorter->bUsePMA==0 ){
if( pSorter->pRecord ){
SorterThread *pThread = &pSorter->aThread[0];
*pbEof = 0;
pThread->pList = pSorter->pRecord;
pThread->eWork = SORTER_THREAD_SORT;
assert( pThread->aListMemory==0 );
pThread->aListMemory = pSorter->aMemory;
rc = vdbeSorterRunThread(pThread);
pThread->aListMemory = 0;
pSorter->pRecord = pThread->pList;
pThread->pList = 0;
}else{
*pbEof = 1;
}
return rc;
}
/* Write the current in-memory list to a PMA. */
if( pSorter->pRecord ){
rc = vdbeSorterFlushPMA(db, pCsr, 1);
}
/* Join all threads */
rc = vdbeSorterJoinAll(pSorter, rc);
/* If there are more than SORTER_MAX_MERGE_COUNT PMAs on disk, merge
** some of them together so that this is no longer the case. */
assert( SORTER_MAX_MERGE_COUNT>=SQLITE_MAX_SORTER_THREAD );
if( vdbeSorterCountPMA(pSorter)>SORTER_MAX_MERGE_COUNT ){
int i;
for(i=0; rc==SQLITE_OK && i<SQLITE_MAX_SORTER_THREAD; i++){
SorterThread *pThread = &pSorter->aThread[i];
if( pThread->pTemp1 ){
pThread->nConsolidate = SORTER_MAX_MERGE_COUNT/SQLITE_MAX_SORTER_THREAD;
pThread->eWork = SORTER_THREAD_CONS;
if( i<(SQLITE_MAX_SORTER_THREAD-1) ){
void *pCtx = (void*)pThread;
rc = sqlite3ThreadCreate(&pThread->pThread,vdbeSorterThreadMain,pCtx);
}else{
rc = vdbeSorterRunThread(pThread);
}
}
}
}
/* Join all threads */
rc = vdbeSorterJoinAll(pSorter, rc);
/* Assuming no errors have occurred, set up a merger structure to read
** and merge all remaining PMAs. */
assert( pSorter->pMerger==0 );
if( rc==SQLITE_OK ){
int nIter = 0; /* Number of iterators used */
int i;
SorterMerger *pMerger;
for(i=0; i<SQLITE_MAX_SORTER_THREAD; i++){
nIter += pSorter->aThread[i].nPMA;
}
pSorter->pMerger = pMerger = vdbeSorterMergerNew(nIter);
if( pMerger==0 ){
rc = SQLITE_NOMEM;
}else{
int iIter = 0;
int iThread = 0;
for(iThread=0; iThread<SQLITE_MAX_SORTER_THREAD; iThread++){
int iPMA;
i64 iReadOff = 0;
SorterThread *pThread = &pSorter->aThread[iThread];
for(iPMA=0; iPMA<pThread->nPMA && rc==SQLITE_OK; iPMA++){
i64 nDummy = 0;
VdbeSorterIter *pIter = &pMerger->aIter[iIter++];
rc = vdbeSorterIterInit(pThread, iReadOff, pIter, &nDummy);
iReadOff = pIter->iEof;
}
}
for(i=pMerger->nTree-1; rc==SQLITE_OK && i>0; i--){
rc = vdbeSorterDoCompare(&pSorter->aThread[0], pMerger, i);
}
}
}
if( rc==SQLITE_OK ){
*pbEof = (pSorter->pMerger->aIter[pSorter->pMerger->aTree[1]].pFile==0);
}
return rc;
}
/*
** Advance to the next element in the sorter.
*/
int sqlite3VdbeSorterNext(sqlite3 *db, const VdbeCursor *pCsr, int *pbEof){
VdbeSorter *pSorter = pCsr->pSorter;
int rc; /* Return code */
if( pSorter->pMerger ){
rc = vdbeSorterNext(&pSorter->aThread[0], pSorter->pMerger, pbEof);
}else{
SorterRecord *pFree = pSorter->pRecord;
pSorter->pRecord = pFree->u.pNext;
pFree->u.pNext = 0;
if( pSorter->aMemory==0 ) vdbeSorterRecordFree(db, pFree);
*pbEof = !pSorter->pRecord;
rc = SQLITE_OK;
}
return rc;
}
/*
** Return a pointer to a buffer owned by the sorter that contains the
** current key.
*/
static void *vdbeSorterRowkey(
const VdbeSorter *pSorter, /* Sorter object */
int *pnKey /* OUT: Size of current key in bytes */
){
void *pKey;
if( pSorter->pMerger ){
VdbeSorterIter *pIter;
pIter = &pSorter->pMerger->aIter[ pSorter->pMerger->aTree[1] ];
*pnKey = pIter->nKey;
pKey = pIter->aKey;
}else{
*pnKey = pSorter->pRecord->nVal;
pKey = SRVAL(pSorter->pRecord);
}
return pKey;
}
/*
** Copy the current sorter key into the memory cell pOut.
*/
int sqlite3VdbeSorterRowkey(const VdbeCursor *pCsr, Mem *pOut){
VdbeSorter *pSorter = pCsr->pSorter;
void *pKey; int nKey; /* Sorter key to copy into pOut */
pKey = vdbeSorterRowkey(pSorter, &nKey);
if( sqlite3VdbeMemGrow(pOut, nKey, 0) ){
return SQLITE_NOMEM;
}
pOut->n = nKey;
MemSetTypeFlag(pOut, MEM_Blob);
memcpy(pOut->z, pKey, nKey);
return SQLITE_OK;
}
/*
** Compare the key in memory cell pVal with the key that the sorter cursor
** passed as the first argument currently points to. For the purposes of
** the comparison, ignore the rowid field at the end of each record.
**
** If an error occurs, return an SQLite error code (i.e. SQLITE_NOMEM).
** Otherwise, set *pRes to a negative, zero or positive value if the
** key in pVal is smaller than, equal to or larger than the current sorter
** key.
*/
int sqlite3VdbeSorterCompare(
const VdbeCursor *pCsr, /* Sorter cursor */
Mem *pVal, /* Value to compare to current sorter key */
int nIgnore, /* Ignore this many fields at the end */
int *pRes /* OUT: Result of comparison */
){
VdbeSorter *pSorter = pCsr->pSorter;
SorterThread *pMain = &pSorter->aThread[0];
void *pKey; int nKey; /* Sorter key to compare pVal with */
pKey = vdbeSorterRowkey(pSorter, &nKey);
vdbeSorterCompare(pMain, nIgnore, pVal->z, pVal->n, pKey, nKey, pRes);
return SQLITE_OK;
}