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-rw-r--r--ext/fts5/fts5_hash.c560
1 files changed, 560 insertions, 0 deletions
diff --git a/ext/fts5/fts5_hash.c b/ext/fts5/fts5_hash.c
new file mode 100644
index 0000000..bc9244f
--- /dev/null
+++ b/ext/fts5/fts5_hash.c
@@ -0,0 +1,560 @@
+/*
+** 2014 August 11
+**
+** 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.
+**
+******************************************************************************
+**
+*/
+
+
+
+#include "fts5Int.h"
+
+typedef struct Fts5HashEntry Fts5HashEntry;
+
+/*
+** This file contains the implementation of an in-memory hash table used
+** to accumuluate "term -> doclist" content before it is flused to a level-0
+** segment.
+*/
+
+
+struct Fts5Hash {
+ int eDetail; /* Copy of Fts5Config.eDetail */
+ int *pnByte; /* Pointer to bytes counter */
+ int nEntry; /* Number of entries currently in hash */
+ int nSlot; /* Size of aSlot[] array */
+ Fts5HashEntry *pScan; /* Current ordered scan item */
+ Fts5HashEntry **aSlot; /* Array of hash slots */
+};
+
+/*
+** Each entry in the hash table is represented by an object of the
+** following type. Each object, its key (a nul-terminated string) and
+** its current data are stored in a single memory allocation. The
+** key immediately follows the object in memory. The position list
+** data immediately follows the key data in memory.
+**
+** The data that follows the key is in a similar, but not identical format
+** to the doclist data stored in the database. It is:
+**
+** * Rowid, as a varint
+** * Position list, without 0x00 terminator.
+** * Size of previous position list and rowid, as a 4 byte
+** big-endian integer.
+**
+** iRowidOff:
+** Offset of last rowid written to data area. Relative to first byte of
+** structure.
+**
+** nData:
+** Bytes of data written since iRowidOff.
+*/
+struct Fts5HashEntry {
+ Fts5HashEntry *pHashNext; /* Next hash entry with same hash-key */
+ Fts5HashEntry *pScanNext; /* Next entry in sorted order */
+
+ int nAlloc; /* Total size of allocation */
+ int iSzPoslist; /* Offset of space for 4-byte poslist size */
+ int nData; /* Total bytes of data (incl. structure) */
+ int nKey; /* Length of key in bytes */
+ u8 bDel; /* Set delete-flag @ iSzPoslist */
+ u8 bContent; /* Set content-flag (detail=none mode) */
+ i16 iCol; /* Column of last value written */
+ int iPos; /* Position of last value written */
+ i64 iRowid; /* Rowid of last value written */
+};
+
+/*
+** Eqivalent to:
+**
+** char *fts5EntryKey(Fts5HashEntry *pEntry){ return zKey; }
+*/
+#define fts5EntryKey(p) ( ((char *)(&(p)[1])) )
+
+
+/*
+** Allocate a new hash table.
+*/
+int sqlite3Fts5HashNew(Fts5Config *pConfig, Fts5Hash **ppNew, int *pnByte){
+ int rc = SQLITE_OK;
+ Fts5Hash *pNew;
+
+ *ppNew = pNew = (Fts5Hash*)sqlite3_malloc(sizeof(Fts5Hash));
+ if( pNew==0 ){
+ rc = SQLITE_NOMEM;
+ }else{
+ sqlite3_int64 nByte;
+ memset(pNew, 0, sizeof(Fts5Hash));
+ pNew->pnByte = pnByte;
+ pNew->eDetail = pConfig->eDetail;
+
+ pNew->nSlot = 1024;
+ nByte = sizeof(Fts5HashEntry*) * pNew->nSlot;
+ pNew->aSlot = (Fts5HashEntry**)sqlite3_malloc64(nByte);
+ if( pNew->aSlot==0 ){
+ sqlite3_free(pNew);
+ *ppNew = 0;
+ rc = SQLITE_NOMEM;
+ }else{
+ memset(pNew->aSlot, 0, (size_t)nByte);
+ }
+ }
+ return rc;
+}
+
+/*
+** Free a hash table object.
+*/
+void sqlite3Fts5HashFree(Fts5Hash *pHash){
+ if( pHash ){
+ sqlite3Fts5HashClear(pHash);
+ sqlite3_free(pHash->aSlot);
+ sqlite3_free(pHash);
+ }
+}
+
+/*
+** Empty (but do not delete) a hash table.
+*/
+void sqlite3Fts5HashClear(Fts5Hash *pHash){
+ int i;
+ for(i=0; i<pHash->nSlot; i++){
+ Fts5HashEntry *pNext;
+ Fts5HashEntry *pSlot;
+ for(pSlot=pHash->aSlot[i]; pSlot; pSlot=pNext){
+ pNext = pSlot->pHashNext;
+ sqlite3_free(pSlot);
+ }
+ }
+ memset(pHash->aSlot, 0, pHash->nSlot * sizeof(Fts5HashEntry*));
+ pHash->nEntry = 0;
+}
+
+static unsigned int fts5HashKey(int nSlot, const u8 *p, int n){
+ int i;
+ unsigned int h = 13;
+ for(i=n-1; i>=0; i--){
+ h = (h << 3) ^ h ^ p[i];
+ }
+ return (h % nSlot);
+}
+
+static unsigned int fts5HashKey2(int nSlot, u8 b, const u8 *p, int n){
+ int i;
+ unsigned int h = 13;
+ for(i=n-1; i>=0; i--){
+ h = (h << 3) ^ h ^ p[i];
+ }
+ h = (h << 3) ^ h ^ b;
+ return (h % nSlot);
+}
+
+/*
+** Resize the hash table by doubling the number of slots.
+*/
+static int fts5HashResize(Fts5Hash *pHash){
+ int nNew = pHash->nSlot*2;
+ int i;
+ Fts5HashEntry **apNew;
+ Fts5HashEntry **apOld = pHash->aSlot;
+
+ apNew = (Fts5HashEntry**)sqlite3_malloc64(nNew*sizeof(Fts5HashEntry*));
+ if( !apNew ) return SQLITE_NOMEM;
+ memset(apNew, 0, nNew*sizeof(Fts5HashEntry*));
+
+ for(i=0; i<pHash->nSlot; i++){
+ while( apOld[i] ){
+ unsigned int iHash;
+ Fts5HashEntry *p = apOld[i];
+ apOld[i] = p->pHashNext;
+ iHash = fts5HashKey(nNew, (u8*)fts5EntryKey(p),
+ (int)strlen(fts5EntryKey(p)));
+ p->pHashNext = apNew[iHash];
+ apNew[iHash] = p;
+ }
+ }
+
+ sqlite3_free(apOld);
+ pHash->nSlot = nNew;
+ pHash->aSlot = apNew;
+ return SQLITE_OK;
+}
+
+static int fts5HashAddPoslistSize(
+ Fts5Hash *pHash,
+ Fts5HashEntry *p,
+ Fts5HashEntry *p2
+){
+ int nRet = 0;
+ if( p->iSzPoslist ){
+ u8 *pPtr = p2 ? (u8*)p2 : (u8*)p;
+ int nData = p->nData;
+ if( pHash->eDetail==FTS5_DETAIL_NONE ){
+ assert( nData==p->iSzPoslist );
+ if( p->bDel ){
+ pPtr[nData++] = 0x00;
+ if( p->bContent ){
+ pPtr[nData++] = 0x00;
+ }
+ }
+ }else{
+ int nSz = (nData - p->iSzPoslist - 1); /* Size in bytes */
+ int nPos = nSz*2 + p->bDel; /* Value of nPos field */
+
+ assert( p->bDel==0 || p->bDel==1 );
+ if( nPos<=127 ){
+ pPtr[p->iSzPoslist] = (u8)nPos;
+ }else{
+ int nByte = sqlite3Fts5GetVarintLen((u32)nPos);
+ memmove(&pPtr[p->iSzPoslist + nByte], &pPtr[p->iSzPoslist + 1], nSz);
+ sqlite3Fts5PutVarint(&pPtr[p->iSzPoslist], nPos);
+ nData += (nByte-1);
+ }
+ }
+
+ nRet = nData - p->nData;
+ if( p2==0 ){
+ p->iSzPoslist = 0;
+ p->bDel = 0;
+ p->bContent = 0;
+ p->nData = nData;
+ }
+ }
+ return nRet;
+}
+
+/*
+** Add an entry to the in-memory hash table. The key is the concatenation
+** of bByte and (pToken/nToken). The value is (iRowid/iCol/iPos).
+**
+** (bByte || pToken) -> (iRowid,iCol,iPos)
+**
+** Or, if iCol is negative, then the value is a delete marker.
+*/
+int sqlite3Fts5HashWrite(
+ Fts5Hash *pHash,
+ i64 iRowid, /* Rowid for this entry */
+ int iCol, /* Column token appears in (-ve -> delete) */
+ int iPos, /* Position of token within column */
+ char bByte, /* First byte of token */
+ const char *pToken, int nToken /* Token to add or remove to or from index */
+){
+ unsigned int iHash;
+ Fts5HashEntry *p;
+ u8 *pPtr;
+ int nIncr = 0; /* Amount to increment (*pHash->pnByte) by */
+ int bNew; /* If non-delete entry should be written */
+
+ bNew = (pHash->eDetail==FTS5_DETAIL_FULL);
+
+ /* Attempt to locate an existing hash entry */
+ iHash = fts5HashKey2(pHash->nSlot, (u8)bByte, (const u8*)pToken, nToken);
+ for(p=pHash->aSlot[iHash]; p; p=p->pHashNext){
+ char *zKey = fts5EntryKey(p);
+ if( zKey[0]==bByte
+ && p->nKey==nToken
+ && memcmp(&zKey[1], pToken, nToken)==0
+ ){
+ break;
+ }
+ }
+
+ /* If an existing hash entry cannot be found, create a new one. */
+ if( p==0 ){
+ /* Figure out how much space to allocate */
+ char *zKey;
+ sqlite3_int64 nByte = sizeof(Fts5HashEntry) + (nToken+1) + 1 + 64;
+ if( nByte<128 ) nByte = 128;
+
+ /* Grow the Fts5Hash.aSlot[] array if necessary. */
+ if( (pHash->nEntry*2)>=pHash->nSlot ){
+ int rc = fts5HashResize(pHash);
+ if( rc!=SQLITE_OK ) return rc;
+ iHash = fts5HashKey2(pHash->nSlot, (u8)bByte, (const u8*)pToken, nToken);
+ }
+
+ /* Allocate new Fts5HashEntry and add it to the hash table. */
+ p = (Fts5HashEntry*)sqlite3_malloc64(nByte);
+ if( !p ) return SQLITE_NOMEM;
+ memset(p, 0, sizeof(Fts5HashEntry));
+ p->nAlloc = (int)nByte;
+ zKey = fts5EntryKey(p);
+ zKey[0] = bByte;
+ memcpy(&zKey[1], pToken, nToken);
+ assert( iHash==fts5HashKey(pHash->nSlot, (u8*)zKey, nToken+1) );
+ p->nKey = nToken;
+ zKey[nToken+1] = '\0';
+ p->nData = nToken+1 + 1 + sizeof(Fts5HashEntry);
+ p->pHashNext = pHash->aSlot[iHash];
+ pHash->aSlot[iHash] = p;
+ pHash->nEntry++;
+
+ /* Add the first rowid field to the hash-entry */
+ p->nData += sqlite3Fts5PutVarint(&((u8*)p)[p->nData], iRowid);
+ p->iRowid = iRowid;
+
+ p->iSzPoslist = p->nData;
+ if( pHash->eDetail!=FTS5_DETAIL_NONE ){
+ p->nData += 1;
+ p->iCol = (pHash->eDetail==FTS5_DETAIL_FULL ? 0 : -1);
+ }
+
+ }else{
+
+ /* Appending to an existing hash-entry. Check that there is enough
+ ** space to append the largest possible new entry. Worst case scenario
+ ** is:
+ **
+ ** + 9 bytes for a new rowid,
+ ** + 4 byte reserved for the "poslist size" varint.
+ ** + 1 byte for a "new column" byte,
+ ** + 3 bytes for a new column number (16-bit max) as a varint,
+ ** + 5 bytes for the new position offset (32-bit max).
+ */
+ if( (p->nAlloc - p->nData) < (9 + 4 + 1 + 3 + 5) ){
+ sqlite3_int64 nNew = p->nAlloc * 2;
+ Fts5HashEntry *pNew;
+ Fts5HashEntry **pp;
+ pNew = (Fts5HashEntry*)sqlite3_realloc64(p, nNew);
+ if( pNew==0 ) return SQLITE_NOMEM;
+ pNew->nAlloc = (int)nNew;
+ for(pp=&pHash->aSlot[iHash]; *pp!=p; pp=&(*pp)->pHashNext);
+ *pp = pNew;
+ p = pNew;
+ }
+ nIncr -= p->nData;
+ }
+ assert( (p->nAlloc - p->nData) >= (9 + 4 + 1 + 3 + 5) );
+
+ pPtr = (u8*)p;
+
+ /* If this is a new rowid, append the 4-byte size field for the previous
+ ** entry, and the new rowid for this entry. */
+ if( iRowid!=p->iRowid ){
+ u64 iDiff = (u64)iRowid - (u64)p->iRowid;
+ fts5HashAddPoslistSize(pHash, p, 0);
+ p->nData += sqlite3Fts5PutVarint(&pPtr[p->nData], iDiff);
+ p->iRowid = iRowid;
+ bNew = 1;
+ p->iSzPoslist = p->nData;
+ if( pHash->eDetail!=FTS5_DETAIL_NONE ){
+ p->nData += 1;
+ p->iCol = (pHash->eDetail==FTS5_DETAIL_FULL ? 0 : -1);
+ p->iPos = 0;
+ }
+ }
+
+ if( iCol>=0 ){
+ if( pHash->eDetail==FTS5_DETAIL_NONE ){
+ p->bContent = 1;
+ }else{
+ /* Append a new column value, if necessary */
+ assert_nc( iCol>=p->iCol );
+ if( iCol!=p->iCol ){
+ if( pHash->eDetail==FTS5_DETAIL_FULL ){
+ pPtr[p->nData++] = 0x01;
+ p->nData += sqlite3Fts5PutVarint(&pPtr[p->nData], iCol);
+ p->iCol = (i16)iCol;
+ p->iPos = 0;
+ }else{
+ bNew = 1;
+ p->iCol = (i16)(iPos = iCol);
+ }
+ }
+
+ /* Append the new position offset, if necessary */
+ if( bNew ){
+ p->nData += sqlite3Fts5PutVarint(&pPtr[p->nData], iPos - p->iPos + 2);
+ p->iPos = iPos;
+ }
+ }
+ }else{
+ /* This is a delete. Set the delete flag. */
+ p->bDel = 1;
+ }
+
+ nIncr += p->nData;
+ *pHash->pnByte += nIncr;
+ return SQLITE_OK;
+}
+
+
+/*
+** Arguments pLeft and pRight point to linked-lists of hash-entry objects,
+** each sorted in key order. This function merges the two lists into a
+** single list and returns a pointer to its first element.
+*/
+static Fts5HashEntry *fts5HashEntryMerge(
+ Fts5HashEntry *pLeft,
+ Fts5HashEntry *pRight
+){
+ Fts5HashEntry *p1 = pLeft;
+ Fts5HashEntry *p2 = pRight;
+ Fts5HashEntry *pRet = 0;
+ Fts5HashEntry **ppOut = &pRet;
+
+ while( p1 || p2 ){
+ if( p1==0 ){
+ *ppOut = p2;
+ p2 = 0;
+ }else if( p2==0 ){
+ *ppOut = p1;
+ p1 = 0;
+ }else{
+ int i = 0;
+ char *zKey1 = fts5EntryKey(p1);
+ char *zKey2 = fts5EntryKey(p2);
+ while( zKey1[i]==zKey2[i] ) i++;
+
+ if( ((u8)zKey1[i])>((u8)zKey2[i]) ){
+ /* p2 is smaller */
+ *ppOut = p2;
+ ppOut = &p2->pScanNext;
+ p2 = p2->pScanNext;
+ }else{
+ /* p1 is smaller */
+ *ppOut = p1;
+ ppOut = &p1->pScanNext;
+ p1 = p1->pScanNext;
+ }
+ *ppOut = 0;
+ }
+ }
+
+ return pRet;
+}
+
+/*
+** Extract all tokens from hash table iHash and link them into a list
+** in sorted order. The hash table is cleared before returning. It is
+** the responsibility of the caller to free the elements of the returned
+** list.
+*/
+static int fts5HashEntrySort(
+ Fts5Hash *pHash,
+ const char *pTerm, int nTerm, /* Query prefix, if any */
+ Fts5HashEntry **ppSorted
+){
+ const int nMergeSlot = 32;
+ Fts5HashEntry **ap;
+ Fts5HashEntry *pList;
+ int iSlot;
+ int i;
+
+ *ppSorted = 0;
+ ap = sqlite3_malloc64(sizeof(Fts5HashEntry*) * nMergeSlot);
+ if( !ap ) return SQLITE_NOMEM;
+ memset(ap, 0, sizeof(Fts5HashEntry*) * nMergeSlot);
+
+ for(iSlot=0; iSlot<pHash->nSlot; iSlot++){
+ Fts5HashEntry *pIter;
+ for(pIter=pHash->aSlot[iSlot]; pIter; pIter=pIter->pHashNext){
+ if( pTerm==0
+ || (pIter->nKey+1>=nTerm && 0==memcmp(fts5EntryKey(pIter), pTerm, nTerm))
+ ){
+ Fts5HashEntry *pEntry = pIter;
+ pEntry->pScanNext = 0;
+ for(i=0; ap[i]; i++){
+ pEntry = fts5HashEntryMerge(pEntry, ap[i]);
+ ap[i] = 0;
+ }
+ ap[i] = pEntry;
+ }
+ }
+ }
+
+ pList = 0;
+ for(i=0; i<nMergeSlot; i++){
+ pList = fts5HashEntryMerge(pList, ap[i]);
+ }
+
+ pHash->nEntry = 0;
+ sqlite3_free(ap);
+ *ppSorted = pList;
+ return SQLITE_OK;
+}
+
+/*
+** Query the hash table for a doclist associated with term pTerm/nTerm.
+*/
+int sqlite3Fts5HashQuery(
+ Fts5Hash *pHash, /* Hash table to query */
+ int nPre,
+ const char *pTerm, int nTerm, /* Query term */
+ void **ppOut, /* OUT: Pointer to new object */
+ int *pnDoclist /* OUT: Size of doclist in bytes */
+){
+ unsigned int iHash = fts5HashKey(pHash->nSlot, (const u8*)pTerm, nTerm);
+ char *zKey = 0;
+ Fts5HashEntry *p;
+
+ for(p=pHash->aSlot[iHash]; p; p=p->pHashNext){
+ zKey = fts5EntryKey(p);
+ assert( p->nKey+1==(int)strlen(zKey) );
+ if( nTerm==p->nKey+1 && memcmp(zKey, pTerm, nTerm)==0 ) break;
+ }
+
+ if( p ){
+ int nHashPre = sizeof(Fts5HashEntry) + nTerm + 1;
+ int nList = p->nData - nHashPre;
+ u8 *pRet = (u8*)(*ppOut = sqlite3_malloc64(nPre + nList + 10));
+ if( pRet ){
+ Fts5HashEntry *pFaux = (Fts5HashEntry*)&pRet[nPre-nHashPre];
+ memcpy(&pRet[nPre], &((u8*)p)[nHashPre], nList);
+ nList += fts5HashAddPoslistSize(pHash, p, pFaux);
+ *pnDoclist = nList;
+ }else{
+ *pnDoclist = 0;
+ return SQLITE_NOMEM;
+ }
+ }else{
+ *ppOut = 0;
+ *pnDoclist = 0;
+ }
+
+ return SQLITE_OK;
+}
+
+int sqlite3Fts5HashScanInit(
+ Fts5Hash *p, /* Hash table to query */
+ const char *pTerm, int nTerm /* Query prefix */
+){
+ return fts5HashEntrySort(p, pTerm, nTerm, &p->pScan);
+}
+
+void sqlite3Fts5HashScanNext(Fts5Hash *p){
+ assert( !sqlite3Fts5HashScanEof(p) );
+ p->pScan = p->pScan->pScanNext;
+}
+
+int sqlite3Fts5HashScanEof(Fts5Hash *p){
+ return (p->pScan==0);
+}
+
+void sqlite3Fts5HashScanEntry(
+ Fts5Hash *pHash,
+ const char **pzTerm, /* OUT: term (nul-terminated) */
+ const u8 **ppDoclist, /* OUT: pointer to doclist */
+ int *pnDoclist /* OUT: size of doclist in bytes */
+){
+ Fts5HashEntry *p;
+ if( (p = pHash->pScan) ){
+ char *zKey = fts5EntryKey(p);
+ int nTerm = (int)strlen(zKey);
+ fts5HashAddPoslistSize(pHash, p, 0);
+ *pzTerm = zKey;
+ *ppDoclist = (const u8*)&zKey[nTerm+1];
+ *pnDoclist = p->nData - (sizeof(Fts5HashEntry) + nTerm + 1);
+ }else{
+ *pzTerm = 0;
+ *ppDoclist = 0;
+ *pnDoclist = 0;
+ }
+}
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