Many hyperlinks are disabled.
Use anonymous login
to enable hyperlinks.
Overview
Comment: | :-) (CVS 220) |
---|---|
Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
45a0e0fc8ccde52ac409d1271beaef77 |
User & Date: | drh 2001-05-26 13:15:44.000 |
Context
2001-05-28
| ||
00:41 | :-) (CVS 221) (check-in: c8d3bdd91e user: drh tags: trunk) | |
2001-05-26
| ||
13:15 | :-) (CVS 220) (check-in: 45a0e0fc8c user: drh tags: trunk) | |
2001-05-24
| ||
21:06 | Continued work on btree (CVS 219) (check-in: 18500cdcc1 user: drh tags: trunk) | |
Changes
Changes to src/btree.c.
︙ | ︙ | |||
17 18 19 20 21 22 23 | ** Boston, MA 02111-1307, USA. ** ** Author contact information: ** drh@hwaci.com ** http://www.hwaci.com/drh/ ** ************************************************************************* | | < < < < < < < < < < < < < < < < < < < < < < < < < > | 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 | ** Boston, MA 02111-1307, USA. ** ** Author contact information: ** drh@hwaci.com ** http://www.hwaci.com/drh/ ** ************************************************************************* ** $Id: btree.c,v 1.8 2001/05/26 13:15:44 drh Exp $ */ #include "sqliteInt.h" #include "pager.h" #include "btree.h" #include <assert.h> /* ** Primitive data types. u32 must be 4 bytes and u16 must be 2 bytes. ** Change these typedefs when porting to new architectures. */ typedef unsigned int u32; typedef unsigned short int u16; /* ** Forward declarations of structures used only in this file. */ typedef struct Page1Header Page1Header; typedef struct MemPage MemPage; typedef struct PageHdr PageHdr; typedef struct Cell Cell; typedef struct CellHdr CellHdr; typedef struct FreeBlk FreeBlk; typedef struct OverflowPage OverflowPage; /* ** All structures on a database page are aligned to 4-byte boundries. ** This routine rounds up a number of bytes to the next multiple of 4. ** |
︙ | ︙ | |||
114 115 116 117 118 119 120 121 122 123 124 125 | */ struct PageHdr { Pgno pgno; /* Child page that comes after all cells on this page */ u16 firstCell; /* Index in MemPage.aPage[] of the first cell */ u16 firstFree; /* Index in MemPage.aPage[] of the first free block */ }; /* ** Data on a database page is stored as a linked list of Cell structures. ** Both the key and the data are stored in aData[]. The key always comes ** first. The aData[] field grows as necessary to hold the key and data, ** up to a maximum of MX_LOCAL_PAYLOAD bytes. If the size of the key and | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > | | | > > > > > < | < < | > > > > > > | 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 | */ struct PageHdr { Pgno pgno; /* Child page that comes after all cells on this page */ u16 firstCell; /* Index in MemPage.aPage[] of the first cell */ u16 firstFree; /* Index in MemPage.aPage[] of the first free block */ }; /* ** Entries on a page of the database are called "Cells". Each Cell ** has a header and data. This structure defines the header. The ** definition of the complete Cell including the data is given below. */ struct CellHdr { Pgno pgno; /* Child page that comes before this cell */ u16 nKey; /* Number of bytes in the key */ u16 iNext; /* Index in MemPage.aPage[] of next cell in sorted order */ u32 nData; /* Number of bytes of data */ } /* ** The minimum size of a complete Cell. The Cell must contain a header ** and at least 4 bytes of data. */ #define MIN_CELL_SIZE (sizeof(CellHdr)+4) /* ** The maximum number of database entries that can be held in a single ** page of the database. */ #define MX_CELL ((SQLITE_PAGE_SIZE-sizeof(PageHdr))/MIN_CELL_SIZE) /* ** The maximum amount of data (in bytes) that can be stored locally for a ** database entry. If the entry contains more data than this, the ** extra goes onto overflow pages. */ #define MX_LOCAL_PAYLOAD \ ((SQLITE_PAGE_SIZE-sizeof(PageHdr))/4-(sizeof(CellHdr)+sizeof(Pgno))) /* ** Data on a database page is stored as a linked list of Cell structures. ** Both the key and the data are stored in aData[]. The key always comes ** first. The aData[] field grows as necessary to hold the key and data, ** up to a maximum of MX_LOCAL_PAYLOAD bytes. If the size of the key and ** data combined exceeds MX_LOCAL_PAYLOAD bytes, then Cell.ovfl is the ** page number of the first overflow page. ** ** Though this structure is fixed in size, the Cell on the database ** page varies in size. Very cell has a CellHdr and at least 4 bytes ** of payload space. Additional payload bytes (up to the maximum of ** MX_LOCAL_PAYLOAD) and the Cell.ovfl value are allocated only as ** needed. */ struct Cell { CellHdr h; /* The cell header */ char aData[MX_LOCAL_PAYLOAD]; /* Key and data */ Pgno ovfl; /* The first overflow page */ }; /* ** Free space on a page is remembered using a linked list of the FreeBlk ** structures. Space on a database page is allocated in increments of ** at least 4 bytes and is always aligned to a 4-byte boundry. The ** linked list of freeblocks is always kept in order by address. */ struct FreeBlk { u16 iSize; /* Number of bytes in this block of free space */ u16 iNext; /* Index in MemPage.aPage[] of the next free block */ }; /* ** Number of bytes on a single overflow page. */ #define OVERFLOW_SIZE (SQLITE_PAGE_SIZE-sizeof(Pgno)) /* ** When the key and data for a single entry in the BTree will not fit in ** the MX_LOACAL_PAYLOAD bytes of space available on the database page, ** then all extra data is written to a linked list of overflow pages. ** Each overflow page is an instance of the following structure. ** ** Unused pages in the database are also represented by instances of |
︙ | ︙ | |||
190 191 192 193 194 195 196 197 198 199 200 201 202 203 | int idxStart; /* Index in aPage[] of real data */ PageHdr *pStart; /* Points to aPage[idxStart] */ int nFree; /* Number of free bytes in aPage[] */ int nCell; /* Number of entries on this page */ Cell *aCell[MX_CELL]; /* All data entires in sorted order */ } /* ** Everything we need to know about an open database */ struct Btree { Pager *pPager; /* The page cache */ BtCursor *pCursor; /* A list of all open cursors */ MemPage *page1; /* First page of the database */ | > > > > > > > | 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 | int idxStart; /* Index in aPage[] of real data */ PageHdr *pStart; /* Points to aPage[idxStart] */ int nFree; /* Number of free bytes in aPage[] */ int nCell; /* Number of entries on this page */ Cell *aCell[MX_CELL]; /* All data entires in sorted order */ } /* ** The in-memory image of a disk page has the auxiliary information appended ** to the end. EXTRA_SIZE is the number of bytes of space needed to hold ** that extra information. */ #define EXTRA_SIZE (sizeof(MemPage)-SQLITE_PAGE_SIZE) /* ** Everything we need to know about an open database */ struct Btree { Pager *pPager; /* The page cache */ BtCursor *pCursor; /* A list of all open cursors */ MemPage *page1; /* First page of the database */ |
︙ | ︙ | |||
213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 | struct BtCursor { Btree *pBt; /* The pointer back to the BTree */ BtCursor *pPrev, *pNext; /* List of all cursors */ MemPage *pPage; /* Page that contains the entry */ int idx; /* Index of the entry in pPage->aCell[] */ int skip_incr; /* */ }; /* ** Defragment the page given. All Cells are moved to the ** beginning of the page and all free space is collected ** into one big FreeBlk at the end of the page. */ static void defragmentPage(MemPage *pPage){ int pc; int i, n; FreeBlk *pFBlk; char newPage[SQLITE_PAGE_SIZE]; pc = ROUNDUP(pPage->idxStart + sizeof(PageHdr)); pPage->pStart->firstCell = pc; memcpy(newPage, pPage->aPage, pc); for(i=0; i<pPage->nCell; i++){ Cell *pCell = &pPage->aCell[i]; | > > > > > > > > > > > > > > > > < < | < | | 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 | struct BtCursor { Btree *pBt; /* The pointer back to the BTree */ BtCursor *pPrev, *pNext; /* List of all cursors */ MemPage *pPage; /* Page that contains the entry */ int idx; /* Index of the entry in pPage->aCell[] */ int skip_incr; /* */ }; /* ** Compute the total number of bytes that a Cell needs on the main ** database page. The number returned includes the Cell header, but ** not any overflow pages. */ static int cellSize(Cell *pCell){ int n = pCell->h.nKey + pCell->h.nData; if( n>MX_LOCAL_PAYLOAD ){ n = MX_LOCAL_PAYLOAD + sizeof(Pgno); }else{ n = ROUNDUP(n); } n += sizeof(CellHdr); return n; } /* ** Defragment the page given. All Cells are moved to the ** beginning of the page and all free space is collected ** into one big FreeBlk at the end of the page. */ static void defragmentPage(MemPage *pPage){ int pc; int i, n; FreeBlk *pFBlk; char newPage[SQLITE_PAGE_SIZE]; pc = ROUNDUP(pPage->idxStart + sizeof(PageHdr)); pPage->pStart->firstCell = pc; memcpy(newPage, pPage->aPage, pc); for(i=0; i<pPage->nCell; i++){ Cell *pCell = &pPage->aCell[i]; n = cellSize(pCell); pCell->h.iNext = i<pPage->nCell ? pc + n : 0; memcpy(&newPage[pc], pCell, n); pPage->aCell[i] = (Cell*)&pPage->aPage[pc]; pc += n; } assert( pPage->nFree==SQLITE_PAGE_SIZE-pc ); memcpy(pPage->aPage, newPage, pc); pFBlk = &pPage->aPage[pc]; |
︙ | ︙ | |||
363 364 365 366 367 368 369 | pPage->isInit = 1; assert( pPage->pParent==0 ); pPage->pParent = pParent; if( pParent ) sqlitepager_ref(pParent); pPage->nCell = 0; idx = pPage->pStart->firstCell; while( idx!=0 ){ | | | | 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 | pPage->isInit = 1; assert( pPage->pParent==0 ); pPage->pParent = pParent; if( pParent ) sqlitepager_ref(pParent); pPage->nCell = 0; idx = pPage->pStart->firstCell; while( idx!=0 ){ if( idx>SQLITE_PAGE_SIZE-MN_CELL_SIZE ) goto page_format_error; if( idx<pPage->idxStart + sizeof(PageHeader) ) goto page_format_error; pCell = (Cell*)&pPage->aPage[idx]; pPage->aCell[pPage->nCell++] = pCell; idx = pCell->h.iNext; } pPage->nFree = 0; idx = pPage->pStart->firstFree; while( idx!=0 ){ if( idx>SQLITE_PAGE_SIZE-sizeof(FreeBlk) ) goto page_format_error; if( idx<pPage->idxStart + sizeof(PageHeader) ) goto page_format_error; pFBlk = (FreeBlk*)&pPage->aPage[idx]; |
︙ | ︙ | |||
614 615 616 617 618 619 620 | pPage = pCur->pPage; assert( pPage!=0 ); if( pCur->idx >= pPage->nCell ){ *pSize = 0; }else{ pCell = pPage->aCell[pCur->idx]; | | | 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 | pPage = pCur->pPage; assert( pPage!=0 ); if( pCur->idx >= pPage->nCell ){ *pSize = 0; }else{ pCell = pPage->aCell[pCur->idx]; *psize = pCell->h.nKey; } return SQLITE_OK; } /* ** Read payload information from the entry that the pCur cursor is ** pointing to. Begin reading the payload at "offset" and read |
︙ | ︙ | |||
692 693 694 695 696 697 698 | if( amt==0 ) return SQLITE_OK; pPage = pCur->pPage; assert( pPage!=0 ); if( pCur->idx >= pPage->nCell ){ return SQLITE_ERROR; } pCell = pPage->aCell[pCur->idx]; | | | | 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 | if( amt==0 ) return SQLITE_OK; pPage = pCur->pPage; assert( pPage!=0 ); if( pCur->idx >= pPage->nCell ){ return SQLITE_ERROR; } pCell = pPage->aCell[pCur->idx]; if( amt+offset > pCell->h.nKey ){ return getPayload(pCur, offset, amt, zBuf); } /* ** Write the number of bytes of data on the entry that the cursor ** is pointing to into *pSize. Return SQLITE_OK. Failure is ** not possible. */ int sqliteBtreeDataSize(BtCursor *pCur, int *pSize){ Cell *pCell; MemPage *pPage; pPage = pCur->pPage; assert( pPage!=0 ); if( pCur->idx >= pPage->nCell ){ *pSize = 0; }else{ pCell = pPage->aCell[pCur->idx]; *pSize = pCell->h.nData; } return SQLITE_OK; } /* ** Read part of the data associated with cursor pCur. A total ** of "amt" bytes will be transfered into zBuf[]. The transfer |
︙ | ︙ | |||
736 737 738 739 740 741 742 | if( amt==0 ) return SQLITE_OK; pPage = pCur->pPage; assert( pPage!=0 ); if( pCur->idx >= pPage->nCell ){ return SQLITE_ERROR; } pCell = pPage->aCell[pCur->idx]; | | | | 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 | if( amt==0 ) return SQLITE_OK; pPage = pCur->pPage; assert( pPage!=0 ); if( pCur->idx >= pPage->nCell ){ return SQLITE_ERROR; } pCell = pPage->aCell[pCur->idx]; if( amt+offset > pCell->h.nKey ){ return getPayload(pCur, offset + pCell->h.nKey, amt, zBuf); } /* ** Compare the key for the entry that pCur points to against the ** given key (pKey,nKeyOrig). Put the comparison result in *pResult. ** The result is negative if pCur<pKey, zero if they are equal and ** positive if pCur>pKey. |
︙ | ︙ | |||
760 761 762 763 764 765 766 | int nKey = nKeyOrig; int n; Cell *pCell; assert( pCur->pPage ); assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell ); pCell = &pCur->pPage->aCell[pCur->idx]; | | | | | 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 | int nKey = nKeyOrig; int n; Cell *pCell; assert( pCur->pPage ); assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell ); pCell = &pCur->pPage->aCell[pCur->idx]; if( nKey > pCell->h.nKey ){ nKey = pCell->h.nKey; } n = nKey; if( n>MX_LOCAL_PAYLOAD ){ n = MX_LOCAL_PAYLOAD; } c = memcmp(pCell->aData, pKey, n); if( c!=0 ){ *pResult = c; return SQLITE_OK; } pKey += n; nKey -= n; nextPage = pCell->ovfl; while( nKey>0 ){ OverflowPage *pOvfl; if( nextPage==0 ){ return SQLITE_CORRUPT; } rc = sqlitepager_get(pCur->pBt->pPager, nextPage, &pOvfl); if( rc ){ |
︙ | ︙ | |||
798 799 800 801 802 803 804 | if( c!=0 ){ *pResult = c; return SQLITE_OK; } nKey -= n; pKey += n; } | | | 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 | if( c!=0 ){ *pResult = c; return SQLITE_OK; } nKey -= n; pKey += n; } c = pCell->h.nKey - nKeyOrig; *pResult = c; return SQLITE_OK; } /* ** Move the cursor down to a new child page. */ |
︙ | ︙ | |||
840 841 842 843 844 845 846 | return SQLITE_INTERNAL; } sqlitepager_ref(pParent); sqlitepager_unref(pCur->pPage); pCur->pPage = pParent; pCur->idx = pPage->nCell; for(i=0; i<pPage->nCell; i++){ | | | 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 | return SQLITE_INTERNAL; } sqlitepager_ref(pParent); sqlitepager_unref(pCur->pPage); pCur->pPage = pParent; pCur->idx = pPage->nCell; for(i=0; i<pPage->nCell; i++){ if( pPage->aCell[i].h.pgno==oldPgno ){ pCur->idx = i; break; } } } /* |
︙ | ︙ | |||
950 951 952 953 954 955 956 | if( rc ) return rc; pPage = pCur->pPage; } if( pRes ) *pRes = 0; return SQLITE_OK; } | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > | > | 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 | if( rc ) return rc; pPage = pCur->pPage; } if( pRes ) *pRes = 0; return SQLITE_OK; } /* ** Allocate a new page from the database file. ** ** The new page is marked as dirty. (In other words, sqlitepager_write() ** has already been called on the new page.) The new page has also ** been referenced and the calling routine is responsible for calling ** sqlitepager_unref() on the new page when it is done. ** ** SQLITE_OK is returned on success. Any other return value indicates ** an error. *ppPage and *pPgno are undefined in the event of an error. ** Do not invoke sqlitepager_unref() on *ppPage if an error is returned. */ static int allocatePage(Btree *pBt, MemPage **ppPage, Pgno *pPgno){ Page1Header *pPage1 = (Page1Header*)pBt->page1; if( pPage1->freeList ){ OverflowPage *pOvfl; rc = sqlitepager_write(pPage1); if( rc ) return rc; *pPgno = pPage1->freeList; rc = sqlitepager_get(pBt->pPager, pPage1->freeList, &pOvfl); if( rc ) return rc; rc = sqlitepager_write(pOvfl); if( rc ){ sqlitepager_unref(pOvfl); return rc; } pPage1->freeList = pOvfl->next; *ppPage = (MemPage*)pOvfl; }else{ *pPgno = sqlitepager_pagecount(pBt->pPager); rc = sqlitepager_get(pBt->pPager, *pPgno, ppPage); if( rc ) return rc; rc = sqlitepager_write(*ppPage); } return rc; } /* ** Add a page of the database file to the freelist. Either pgno or ** pPage but not both may be 0. */ static int freePage(Btree *pBt, void *pPage, Pgno pgno){ Page1Header *pPage1 = (Page1Header*)pBt->page1; OverflowPage *pOvfl = (OverflowPage*)pPage; int rc; int needOvflUnref = 0; if( pgno==0 ){ assert( pOvfl!=0 ); pgno = sqlitepager_pagenumber(pOvfl); } rc = sqlitepager_write(pPage1); if( rc ){ return rc; } if( pOvfl==0 ){ assert( pgno>0 ); rc = sqlitepager_get(pBt->pPager, pgno, &pOvfl); if( rc ) return rc; needOvflUnref = 1; } rc = sqlitepager_write(pOvfl); if( rc ){ if( needOvflUnref ) sqlitepager_unref(pOvfl); return rc; } pOvfl->next = pPage1->freeList; pPage1->freeList = pgno; memset(pOvfl->aData, 0, OVERFLOW_SIZE); rc = sqlitepager_unref(pOvfl); return rc; } /* ** Erase all the data out of a cell. This involves returning overflow ** pages back the freelist. */ static int clearCell(Btree *pBt, Cell *pCell){ Pager *pPager = pBt->pPager; OverflowPage *pOvfl; Page1Header *pPage1 = (Page1Header*)pBt->page1; Pgno ovfl, nextOvfl; int rc; ovfl = pCell->ovfl; pCell->ovfl = 0; while( ovfl ){ rc = sqlitepager_get(pPager, ovfl, &pOvfl); if( rc ) return rc; nextOvfl = pOvfl->next; freePage(pBt, pOvfl, ovfl); ovfl = nextOvfl; sqlitepager_unref(pOvfl); } } /* ** Create a new cell from key and data. Overflow pages are allocated as ** necessary and linked to this cell. */ static int fillInCell( Btree *pBt, /* The whole Btree. Needed to allocate pages */ Cell *pCell, /* Populate this Cell structure */ void *pKey, int nKey, /* The key */ void *pData,int nData /* The data */ ){ int OverflowPage *pOvfl; Pgno *pNext; int spaceLeft; int n; int nPayload; char *pPayload; char *pSpace; pCell->h.pgno = 0; pCell->h.nKey = nKey; pCell->h.nData = nData; pCell->h.iNext = 0; pNext = &pCell->ovfl; pSpace = pCell->aData; spaceLeft = MX_LOCAL_PAYLOAD; pPayload = pKey; pKey = 0; nPayload = nKey; while( nPayload>0 ){ if( spaceLeft==0 ){ rc = allocatePage(pBt, &pOvfl, pNext); if( rc ){ *pNext = 0; clearCell(pCell); return rc; } spaceLeft = OVERFLOW_SIZE; pSpace = pOvfl->aData; pNextPg = &pOvfl->next; } n = nPayload; if( n>spaceLeft ) n = spaceLeft; memcpy(pSpace, pPayload, n); nPayload -= n; if( nPayload==0 && pData ){ pPayload = pData; nPayload = nData; pData = 0; }else{ pPayload += n; } spaceLeft -= n; pSpace += n; } return SQLITE_OK; } /* ** Attempt to move N or more bytes out of the page that the cursor ** points to into the left sibling page. (The left sibling page ** contains cells that are less than the cells on this page.) Return ** TRUE if successful and FALSE if not. ** ** Reasons for not being successful include: ** ** (1) there is no left sibling, ** (2) we could only move N-1 bytes or less, ** (3) some kind of file I/O error occurred */ static int rotateLeft(BtCursor *pCur, int N){ } /* ** Split a single database page into two roughly equal-sized pages. ** ** The input is an existing page and a new Cell. The Cell might contain ** a valid Cell.pgno field pointing to a child page. ** ** The output is the Cell that divides the two new pages. The content ** of this divider Cell is written into *pCenter. pCenter->pgno points ** to the new page that was created to hold the smaller half of the ** cells from the divided page. The larger cells from the divided ** page are written to a newly allocated page and *ppOut is made to ** point to that page. Except, if ppOut==NULL then the larger cells ** remain on pIn. */ static int split( MemPage *pIn, /* The page that is to be divided */ Cell *pNewCell, /* A new cell to add to pIn before dividing it up */ Cell *pCenter, /* Write the cell that divides the two pages here */ MemPage **ppOut /* If not NULL, put larger cells in new page at *ppOut */ ){ } /* ** With this routine, we know that the Cell pNewCell will fit into the ** database page that pCur points to. The calling routine has made ** sure it will fit. All this routine needs to do is add the Cell ** to the page. */ static int insertCell(BtCursor *pCur, Cell *pNewCell){ } /* ** Insert pNewCell into the database page that pCur is pointing to. ** pNewCell->h.pgno points to a child page that comes before pNewCell->data[], ** unless pCur is a leaf page. */ static int addToPage(BtCursor *pCur, Cell *pNewCell){ Cell tempCell; Cell centerCell; for(;;){ MemPage *pPage = pCur->pPage; int sz = cellSize(pNewCell); if( sz<=pPage->nFree ){ insertCell(pCur, pNewCell); return SQLITE_OK; } if( pPage->pParent==0 ){ MemPage *pRight; PageHdr *pHdr; FreeBlk *pFBlk; int pc; rc = split(pPage, pNewCell, ¢erCell, &pRight); pHdr = pPage->pStart; pHdr->pgno = sqlitepager_pagenumber(pRight); sqlitepager_unref(pRight); pHdr->firstCell = pc = pPage->idxStart + sizeof(*pHdr); sz = cellSize(¢erCell); memcpy(&pPage->aPage[pc], ¢erCell, sz); pc += sz; pHdr->firstFree = pc; pFBlk = (FreeBlk*)&pPage->aPage[pc]; pFBlk->iSize = SQLITE_PAGE_SIZE - pc; pFBlk->iNext = 0; memset(&pFBlk[1], 0, pFBlk->iSize-sizeof(*pFBlk)); return SQLITE_OK; } if( rotateLeft(pCur, sz - pPage->nFree) || rotateRight(pCur, sz - pPage->nFree) ){ insertCell(pCur, pNewCell); return SQLITE_OK; } rc = split(pPage, pNewCell, ¢erCell, 0); parentPage(pCur); tempCell = centerCell; pNewPage = &tempCell; } } /* ** Insert a new record into the BTree. The key is given by (pKey,nKey) ** and the data is given by (pData,nData). The cursor is used only to ** define what database the record should be inserted into. The cursor ** is NOT left pointing at the new record. */ int sqliteBtreeInsert( BtCursor *pCur, /* Insert data into the table of this cursor */ void *pKey, int nKey, /* The key of the new record */ void *pData, int nData /* The data of the new record */ ){ Cell newCell; int rc; int loc; MemPage *pPage; Btree *pBt = pCur->pBt; rc = sqliteBtreeMoveTo(pCur, pKey, nKey, &loc); if( rc ) return rc; rc = fillInCell(pBt, &newCell, pKey, nKey, pData, nData); if( rc ) return rc; newCell.h.pgno = pCur->pPage->aCell[pCur->idx].h.pgno; if( loc==0 ){ rc = clearCell(pBt, &pCur->pPage->aCell[pCur->idx]); if( rc ){ return SQLITE_CORRUPT; } unlinkCell(pCur); } return addToPage(pCur, &newCell); } /* ** Delete the record that the cursor is pointing to. Leave the cursor ** pointing at the next record after the one to which it currently points. ** Also, set the pCur->skip_next flag so that the next sqliteBtreeNext() ** called for this cursor will be a no-op. */ int sqliteBtreeDelete(BtCursor *pCur){ } |