sqlite3-wasm.c: code legibility and coding style tweaks. Increase SQLITE_DEFAULT_PAGE_SIZE from 4k to 8k, as that improves OPFS speedtest1 performance by roughly 12%.

FossilOrigin-Name: c260895faacb3458c557778630756d02a8520c0f1864bddcf86cdd27ef4a42bd

ext/wasm/api/sqlite3-wasm.c

@@ -32,21 +32,16 @@
 ** the same db handle as another thread, thus multi-threading support
 ** is unnecessary in the library. Because the filesystems are virtual
 ** and local to a given wasm runtime instance, two Workers can never
-** access the same db file at once, with the exception of OPFS. As of
-** this writing (2022-09-30), OPFS exclusively locks a file when
-** opening it, so two Workers can never open the same OPFS-backed file
-** at once. That situation will change if and when lower-level locking
-** features are added to OPFS (as is currently planned, per folks
-** involved with its development).
+** access the same db file at once, with the exception of OPFS.
 **
-** Summary: except for the case of future OPFS, which supports
-** locking, and any similar future filesystems, threading and file
-** locking support are unnecessary in the wasm build.
+** Summary: except for the case of OPFS, which supports locking using
+** its own API, threading and file locking support are unnecessary in
+** the wasm build.
 */
 
 /*
 ** Undefine any SQLITE_... config flags which we specifically do not
-** want undefined. Please keep these alphabetized.
+** want defined. Please keep these alphabetized.
 */
 #undef SQLITE_OMIT_DESERIALIZE
 #undef SQLITE_OMIT_MEMORYDB
@@ -69,9 +64,11 @@
 */
 # define SQLITE_DEFAULT_CACHE_SIZE -16384
 #endif
-#if 0 && !defined(SQLITE_DEFAULT_PAGE_SIZE)
-/* TODO: experiment with this. */
-# define SQLITE_DEFAULT_PAGE_SIZE 8192 /*4096*/
+#if !defined(SQLITE_DEFAULT_PAGE_SIZE)
+/* OPFS performance is improved with a page size of 8k instead
+** of 4k. kvvfs, OTOH, likely suffers from that. Peformance
+** with 16k is equivalent to 8k. */
+# define SQLITE_DEFAULT_PAGE_SIZE 8196 /*4096*/
 #endif
 #ifndef SQLITE_DEFAULT_UNIX_VFS
 # define SQLITE_DEFAULT_UNIX_VFS "unix-none"
@@ -861,9 +858,11 @@ int sqlite3_wasm_db_reset(sqlite3*pDb){
   int rc = SQLITE_MISUSE;
   if( pDb ){
     rc = sqlite3_db_config(pDb, SQLITE_DBCONFIG_RESET_DATABASE, 1, 0);
-    if( 0==rc ) rc = sqlite3_exec(pDb, "VACUUM", 0, 0, 0);
+    if( 0==rc ){
+      rc = sqlite3_exec(pDb, "VACUUM", 0, 0, 0);
       sqlite3_db_config(pDb, SQLITE_DBCONFIG_RESET_DATABASE, 0, 0);
     }
+  }
   return rc;
 }
 
@@ -958,9 +957,8 @@ int sqlite3_wasm_db_serialize( sqlite3 *pDb, const char *zSchema,
 ** Emscripten's FS.createDataFile() in a VFS-agnostic way. This
 ** functionality is intended for use in uploading database files.
 **
-** Note that not all VFSes support this operation because they impose
-** specific requirements on truncate and write sizes. e.g.  kvvfs does
-** not work with this.
+** Not all VFSes support this functionality, e.g. the "kvvfs" does
+** not.
 **
 ** If pVfs is NULL, sqlite3_vfs_find(0) is used.
 **
@@ -973,10 +971,7 @@ int sqlite3_wasm_db_serialize( sqlite3 *pDb, const char *zSchema,
 **
 ** Whether or not directory components of zFilename are created
 ** automatically or not is unspecified: that detail is left to the
-** VFS. The "opfs" VFS, for example, create them.
-**
-** Not all VFSes support this functionality, e.g. the "kvvfs" does
-** not.
+** VFS. The "opfs" VFS, for example, creates them.
 **
 ** If an error happens while populating or truncating the file, the
 ** target file will be deleted (if needed) if this function created
@@ -1014,7 +1009,8 @@ int sqlite3_wasm_vfs_create_file( sqlite3_vfs *pVfs,
   pVfs->xAccess(pVfs, zFilename, SQLITE_ACCESS_EXISTS, &fileExisted);
   rc = sqlite3OsOpenMalloc(pVfs, zFilename, &pFile, openFlags, &flagsOut);
 #if 0
-# define RC fprintf(stderr,"create_file(%s,%s) @%d rc=%d\n", pVfs->zName, zFilename, __LINE__, rc);
+# define RC fprintf(stderr,"create_file(%s,%s) @%d rc=%d\n", \
+                    pVfs->zName, zFilename, __LINE__, rc);
 #else
 # define RC
 #endif
@@ -1046,11 +1042,14 @@ int sqlite3_wasm_vfs_create_file( sqlite3_vfs *pVfs,
     }
     if( 0==rc && nData>0 ){
       assert( nData<blockSize );
-      rc = pIo->xWrite(pFile, pPos, nData, (sqlite3_int64)(pPos - pData));
+      rc = pIo->xWrite(pFile, pPos, nData,
+                       (sqlite3_int64)(pPos - pData));
       RC;
     }
   }
-  if( pIo->xUnlock && doUnlock!=0 ) pIo->xUnlock(pFile, SQLITE_LOCK_NONE);
+  if( pIo->xUnlock && doUnlock!=0 ){
+    pIo->xUnlock(pFile, SQLITE_LOCK_NONE);
+  }
   pIo->xClose(pFile);
   if( rc!=0 && 0==fileExisted ){
     pVfs->xDelete(pVfs, zFilename, 1);

manifest

@@ -1,5 +1,5 @@
-C Expand\sJS\stests\sfor\sdb\sexport/import\sand\sdocument\sreason\sit\scannot\scurrently\swork\swith\skvvfs.\sFix\sa\sminor\sJS\sbuild\sdependencies\sbug.\sUpdate\spage\stitle\swith\sPASS/FAIL\sprefix\sfor\stester1.js\sto\simprove\soverview\swhen\slaunching\smultiple\stest\stabs.\sAdd\sability\sof\stester1\sshould-run-test\spredicates\sto\sreport\swhy\sa\sgiven\stest\sis\sdisabled.
-D 2022-12-02T07:14:56.641
+C sqlite3-wasm.c:\scode\slegibility\sand\scoding\sstyle\stweaks.\sIncrease\sSQLITE_DEFAULT_PAGE_SIZE\sfrom\s4k\sto\s8k,\sas\sthat\simproves\sOPFS\sspeedtest1\sperformance\sby\sroughly\s12%.
+D 2022-12-02T08:29:03.564
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@@ -512,7 +512,7 @@ F ext/wasm/api/sqlite3-opfs-async-proxy.js 9963c78bf6e5ccb5ba28e8597851bd9d980e8
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 F ext/wasm/api/sqlite3-worker1-promiser.js 0c7a9826dbf82a5ed4e4f7bf7816e825a52aff253afbf3350431f5773faf0e4b
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-Z eb02f2c4f6198c757ec0df7e4c3e3028
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 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
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