Add test app for experimenting with multi-worker OPFS concurrency. Tweak OPFS VFS to significantly improve the otherwise "unfortunate" concurrency situation.

FossilOrigin-Name: 96f76e7616f8157a342b9e1c42f7b1feab200d182268871a2b25f67d4ee2564c

1 files changed, 9 insertions, 3 deletions

diff --git a/ext/wasm/api/sqlite3-api-opfs.js b/ext/wasm/api/sqlite3-api-opfs.js
index a3f73cc7b..1fd50dcc6 100644
--- a/ext/wasm/api/sqlite3-api-opfs.js
+++ b/ext/wasm/api/sqlite3-api-opfs.js
@@ -92,7 +92,8 @@ const installOpfsVfs = function callee(options){
   }
   const urlParams = new URL(self.location.href).searchParams;
   if(undefined===options.verbose){
-    options.verbose = urlParams.has('opfs-verbose') ? 3 : 2;
+    options.verbose = urlParams.has('opfs-verbose')
+      ? (+urlParams.get('opfs-verbose') || 2) : 1;
   }
   if(undefined===options.sanityChecks){
     options.sanityChecks = urlParams.has('opfs-sanity-check');
@@ -101,6 +102,8 @@ const installOpfsVfs = function callee(options){
     options.proxyUri = callee.defaultProxyUri;
   }
 
+  //console.warn("OPFS options =",options,self.location);
+
   if('function' === typeof options.proxyUri){
     options.proxyUri = options.proxyUri();
   }
@@ -1154,7 +1157,10 @@ const installOpfsVfs = function callee(options){
         [
           /* Truncate journal mode is faster than delete or wal for
              this vfs, per speedtest1. */
-          "pragma journal_mode=truncate;"
+          "pragma journal_mode=truncate;",
+          /* Set a default busy-timeout handler to help OPFS dbs
+             deal with multi-tab/multi-worker contention. */
+          "pragma busy_timeout=2000;",
           /*
             This vfs benefits hugely from cache on moderate/large
             speedtest1 --size 50 and --size 100 workloads. We currently
@@ -1162,7 +1168,7 @@ const installOpfsVfs = function callee(options){
             sqlite3.wasm. If that policy changes, the cache can
             be set here.
           */
-          //"pragma cache_size=-8388608;"
+          //"pragma cache_size=-16384;"
         ].join("")
       );
     }