RetroZilla/db/sqlite3/preload-cache.patch

Index: build.c
===================================================================
RCS file: /cvsroot/mozilla/db/sqlite3/src/build.c,v
retrieving revision 1.4.8.3
diff -u -u -8 -p -r1.4.8.3 build.c
--- build.c	22 Feb 2006 20:56:28 -0000	1.4.8.3
+++ build.c	11 Apr 2006 17:28:51 -0000
@@ -22,16 +22,19 @@
 **     COMMIT
 **     ROLLBACK
 **
 ** $Id: preload-cache.patch,v 1.1.2.1 2006/04/11 17:33:53 brettw%gmail.com Exp $
 */
 #include "sqliteInt.h"
 #include <ctype.h>
 
+#include "pager.h"
+#include "btree.h"
+
 /*
 ** This routine is called when a new SQL statement is beginning to
 ** be parsed.  Initialize the pParse structure as needed.
 */
 void sqlite3BeginParse(Parse *pParse, int explainFlag){
   pParse->explain = explainFlag;
   pParse->nVar = 0;
 }
@@ -3214,8 +3217,34 @@ KeyInfo *sqlite3IndexKeyinfo(Parse *pPar
   }
 
   if( pParse->nErr ){
     sqliteFree(pKey);
     pKey = 0;
   }
   return pKey;
 }
+
+
+/* See declaration in sqlite3.h for information */
+int sqlite3Preload(sqlite3* db)
+{
+  Pager* pPager;
+  Btree* pBt;
+  int rc;
+  int i;
+  int dbsLoaded = 0;
+
+  for (i = 0; i < db->nDb; i ++) {
+    pBt = db->aDb[i].pBt;
+    if (! pBt)
+      continue;
+    pPager = sqlite3BtreePager(pBt);
+    if (pPager) {
+      rc = sqlite3pager_loadall(pPager);
+      if (rc == SQLITE_OK)
+        dbsLoaded ++;
+    }
+  }
+  if (dbsLoaded == 0)
+    return SQLITE_ERROR;
+  return SQLITE_OK;
+}
Index: pager.c
===================================================================
RCS file: /cvsroot/mozilla/db/sqlite3/src/pager.c,v
retrieving revision 1.3.8.3
diff -u -u -8 -p -r1.3.8.3 pager.c
--- pager.c	22 Feb 2006 20:56:28 -0000	1.3.8.3
+++ pager.c	11 Apr 2006 17:28:51 -0000
@@ -2521,16 +2521,30 @@ int sqlite3pager_release_memory(int nReq
 ** to find a page in the in-memory cache first.  If the page is not already
 ** in memory, this routine goes to disk to read it in whereas _lookup()
 ** just returns 0.  This routine acquires a read-lock the first time it
 ** has to go to disk, and could also playback an old journal if necessary.
 ** Since _lookup() never goes to disk, it never has to deal with locks
 ** or journal files.
 */
 int sqlite3pager_get(Pager *pPager, Pgno pgno, void **ppPage){
+  /* This just passes through to our modified version with a NULL data pointer */
+  return sqlite3pager_get2(pPager, pgno, ppPage, 0);
+}
+
+
+/*
+** This is an internal version of pager_get that takes an extra parameter of
+** data to use to fill the page with. This allows more efficient filling for
+** preloaded data. If this extra parameter is NULL, we'll go to the file.
+**
+** See sqlite3pager_loadall which uses this function.
+*/
+int sqlite3pager_get2(Pager *pPager, Pgno pgno, void **ppPage,
+                      unsigned char* pDataToFill) {
   PgHdr *pPg;
   int rc;
 
   /* The maximum page number is 2^31. Return SQLITE_CORRUPT if a page
   ** number greater than this, or zero, is requested.
   */
   if( pgno>PAGER_MAX_PGNO || pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){
     return SQLITE_CORRUPT_BKPT;
@@ -2676,39 +2690,46 @@ int sqlite3pager_get(Pager *pPager, Pgno
     }
 
     /* Populate the page with data, either by reading from the database
     ** file, or by setting the entire page to zero.
     */
     if( sqlite3pager_pagecount(pPager)<(int)pgno || MEMDB ){
       memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize);
     }else{
-      assert( MEMDB==0 );
-      rc = sqlite3OsSeek(pPager->fd, (pgno-1)*(i64)pPager->pageSize);
-      if( rc==SQLITE_OK ){
-        rc = sqlite3OsRead(pPager->fd, PGHDR_TO_DATA(pPg),
-                              pPager->pageSize);
-      }
-      TRACE3("FETCH %d page %d\n", PAGERID(pPager), pPg->pgno);
-      CODEC(pPager, PGHDR_TO_DATA(pPg), pPg->pgno, 3);
-      if( rc!=SQLITE_OK ){
-        i64 fileSize;
-        int rc2 = sqlite3OsFileSize(pPager->fd, &fileSize);
-        if( rc2!=SQLITE_OK || fileSize>=pgno*pPager->pageSize ){
-	  /* An IO error occured in one of the the sqlite3OsSeek() or
-          ** sqlite3OsRead() calls above. */
-          pPg->pgno = 0;
-          sqlite3pager_unref(PGHDR_TO_DATA(pPg));
-          return rc;
+      if (pDataToFill) {
+        /* Just copy from the given memory */
+        memcpy(PGHDR_TO_DATA(pPg), pDataToFill, pPager->pageSize);
+        CODEC(pPager, PGHDR_TO_DATA(pPg), pPg->pgno, 3);
+      } else {
+        /* Load from disk */
+        assert( MEMDB==0 );
+        rc = sqlite3OsSeek(pPager->fd, (pgno-1)*(i64)pPager->pageSize);
+        if( rc==SQLITE_OK ){
+          rc = sqlite3OsRead(pPager->fd, PGHDR_TO_DATA(pPg),
+                                pPager->pageSize);
+        }
+        TRACE3("FETCH %d page %d\n", PAGERID(pPager), pPg->pgno);
+        CODEC(pPager, PGHDR_TO_DATA(pPg), pPg->pgno, 3);
+        if( rc!=SQLITE_OK ){
+          i64 fileSize;
+          int rc2 = sqlite3OsFileSize(pPager->fd, &fileSize);
+          if( rc2!=SQLITE_OK || fileSize>=pgno*pPager->pageSize ){
+            /* An IO error occured in one of the the sqlite3OsSeek() or
+            ** sqlite3OsRead() calls above. */
+            pPg->pgno = 0;
+            sqlite3pager_unref(PGHDR_TO_DATA(pPg));
+            return rc;
+          }else{
+            clear_simulated_io_error();
+            memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize);
+          }
         }else{
-          clear_simulated_io_error();
-          memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize);
+          TEST_INCR(pPager->nRead);
         }
-      }else{
-        TEST_INCR(pPager->nRead);
       }
     }
 
     /* Link the page into the page hash table */
     h = pager_hash(pgno);
     pPg->pNextHash = pPager->aHash[h];
     pPager->aHash[h] = pPg;
     if( pPg->pNextHash ){
@@ -3773,16 +3794,80 @@ int sqlite3pager_movepage(Pager *pPager,
     DATA_TO_PGHDR(pNeedSync)->dirty = 1;
     sqlite3pager_unref(pNeedSync);
   }
 
   return SQLITE_OK;
 }
 #endif
 
+
+/**
+ * Addition for Mozilla: This will attempt to populate the database cache with
+ * the first N bytes of the file, where N is the total size of the cache.
+ * Because we can load this as one chunk from the disk, this is much faster
+ * than loading a subset of the pages one at a time in random order.
+ *
+ * The pager must be initialized before this function is called. This means a
+ * statement must be open that has initialized the pager and is keeping the
+ * cache in memory.
+ */
+int sqlite3pager_loadall(Pager* pPager)
+{
+  int i;
+  int rc;
+  int loadSize;
+  int loadPages;
+  unsigned char* fileData;
+
+  if (pPager->dbSize < 0 || pPager->pageSize < 0) {
+    /* pager not initialized, this means a statement is not open */
+    return SQLITE_MISUSE;
+  }
+
+  /* compute sizes */
+  if (pPager->mxPage < pPager->dbSize)
+    loadPages = pPager->mxPage;
+  else
+    loadPages = pPager->dbSize;
+  loadSize = loadPages * pPager->pageSize;
+
+  rc = sqlite3OsSeek(pPager->fd, 0);
+  if (rc != SQLITE_OK)
+    return rc;
+
+  /* load the file as one chunk */
+  fileData = sqliteMallocRaw(loadSize);
+  if (! fileData)
+    return SQLITE_NOMEM;
+  rc = sqlite3OsRead(pPager->fd, fileData, loadSize);
+  if (rc != SQLITE_OK) {
+    sqliteFree(fileData);
+    return rc;
+  }
+
+  /* Copy the data to each page. Note that the page numbers we pass to _get
+   * are one-based, 0 is a marker for no page. We also need to check that we
+   * haven't loaded more pages than the cache can hold total. There may have
+   * already been a few pages loaded before, so we may fill the cache before
+   * loading all of the pages we want to.
+   */
+  for (i = 1; i <= loadPages && pPager->nPage < pPager->mxPage; i ++) {
+    void *pPage;
+    rc = sqlite3pager_get2(pPager, 1, &pPage,
+                           &fileData[(i-1)*(i64)pPager->pageSize]);
+    if (rc != SQLITE_OK)
+      break;
+    sqlite3pager_unref(pPage);
+  }
+  sqliteFree(fileData);
+  return SQLITE_OK;
+}
+
+
 #if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
 /*
 ** Return the current state of the file lock for the given pager.
 ** The return value is one of NO_LOCK, SHARED_LOCK, RESERVED_LOCK,
 ** PENDING_LOCK, or EXCLUSIVE_LOCK.
 */
 int sqlite3pager_lockstate(Pager *pPager){
   return sqlite3OsLockState(pPager->fd);
Index: pager.h
===================================================================
RCS file: /cvsroot/mozilla/db/sqlite3/src/pager.h,v
retrieving revision 1.2.8.3
diff -u -u -8 -p -r1.2.8.3 pager.h
--- pager.h	22 Feb 2006 20:56:28 -0000	1.2.8.3
+++ pager.h	11 Apr 2006 17:28:51 -0000
@@ -104,16 +104,17 @@ const char *sqlite3pager_filename(Pager*
 const char *sqlite3pager_dirname(Pager*);
 const char *sqlite3pager_journalname(Pager*);
 int sqlite3pager_nosync(Pager*);
 int sqlite3pager_rename(Pager*, const char *zNewName);
 void sqlite3pager_set_codec(Pager*,void(*)(void*,void*,Pgno,int),void*);
 int sqlite3pager_movepage(Pager*,void*,Pgno);
 int sqlite3pager_reset(Pager*);
 int sqlite3pager_release_memory(int);
+int sqlite3pager_loadall(Pager*);
 
 #if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
 int sqlite3pager_lockstate(Pager*);
 #endif
 
 #ifdef SQLITE_TEST
 void sqlite3pager_refdump(Pager*);
 int pager3_refinfo_enable;
Index: sqlite3.h
===================================================================
RCS file: /cvsroot/mozilla/db/sqlite3/src/sqlite3.h,v
retrieving revision 1.2.2.4
diff -u -u -8 -p -r1.2.2.4 sqlite3.h
--- sqlite3.h	22 Feb 2006 20:56:28 -0000	1.2.2.4
+++ sqlite3.h	11 Apr 2006 17:28:51 -0000
@@ -1482,12 +1482,25 @@ int sqlite3_table_column_metadata(
 */
 int sqlite3_bind_parameter_indexes(
     sqlite3_stmt *pStmt,
     const char *zName,
     int **pIndexes
 );
 void sqlite3_free_parameter_indexes(int *pIndexes);
 
+/*
+** Preload the databases into the pager cache, up to the maximum size of the
+** pager cache.
+**
+** For a database to be loaded successfully, the pager must be active. That is,
+** there must be an open statement on that database. See sqlite3pager_loadall
+**
+** There might be many databases attached to the given connection. We iterate
+** them all and try to load them. If none are loadable successfully, we return
+** an error. Otherwise, we return OK.
+*/
+int sqlite3Preload(sqlite3* db);
+
 #ifdef __cplusplus
 }  /* End of the 'extern "C"' block */
 #endif
 #endif