Refactor kvvfs JS bits to make use of [ea370b9b05f7ed7eaa]. At main-thread startup, if kvvfs is available, replace the kvvfs I/O methods with JS impls. Checkin part 2 of 2, to account for cherrypicking [ea370b9b05f7ed7eaa] into the kv-vfs branch.

FossilOrigin-Name: a9047e020a097b2259bc9935b63ca1c538a3a7f1d050e15f0d0a08cfb84acc7c

ext/wasm/api/sqlite3-api-glue.js

@@ -597,6 +597,92 @@ self.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
     }
   }/*end C constant imports*/
 
+  if( util.isMainWindow()
+      && 0!==capi.sqlite3_vfs_find("kvvfs") ){/* kvvfs-specific glue */
+    const kvvfsMethods = new capi.sqlite3_kvvfs_methods(
+      wasm.exports.sqlite3_wasm_kvvfs_methods()
+    );
+    delete capi.sqlite3_kvvfs_methods;
+
+    const kvvfsMakeKey = wasm.exports.sqlite3_wasm_kvvfsMakeKeyOnPstack,
+          pstack = wasm.pstack,
+          pAllocRaw = wasm.exports.sqlite3_wasm_pstack_alloc;
+
+    const kvvfsStorage = (zClass)=>
+          ((115/*=='s'*/===wasm.getMemValue(zClass))
+           ? sessionStorage : localStorage);
+    
+    const kvvfsImpls = {
+      xRead: (zClass, zKey, zBuf, nBuf)=>{
+        const stack = pstack.pointer,
+              astack = wasm.scopedAllocPush();
+        try {
+          const zXKey = kvvfsMakeKey(zClass,zKey);
+          if(!zXKey) return -3/*OOM*/;
+          const jKey = wasm.cstringToJs(zXKey);
+          const jV = kvvfsStorage(zClass).getItem(jKey);
+          if(!jV) return -1;
+          const nV = jV.length /* Note that we are relying 100% on v being
+                                  ASCII so that jV.length is equal to the
+                                  C-string's byte length. */;
+          if(nBuf<=0) return nV;
+          else if(1===nBuf){
+            wasm.setMemValue(zBuf, 0);
+            return nV;
+          }
+          const zV = wasm.scopedAllocCString(jV);
+          if(nBuf > nV + 1) nBuf = nV + 1;
+          wasm.heap8u().copyWithin(zBuf, zV, zV + nBuf - 1);
+          wasm.setMemValue(zBuf + nBuf - 1, 0);
+          return nBuf - 1;
+        }catch(e){
+          console.error("kvstorageRead()",e);
+          return -2;
+        }finally{
+          pstack.restore(stack);
+          wasm.scopedAllocPop(astack);
+        }
+      },
+      xWrite: (zClass, zKey, zData)=>{
+        const stack = pstack.pointer;
+        try {
+          const zXKey = kvvfsMakeKey(zClass,zKey);
+          if(!zXKey) return 1/*OOM*/;
+          const jKey = wasm.cstringToJs(zXKey);
+          kvvfsStorage(zClass).setItem(jKey, wasm.cstringToJs(zData));
+          return 0;
+        }catch(e){
+          console.error("kvstorageWrite()",e);
+          return capi.SQLITE_IOERR;
+        }finally{
+          pstack.restore(stack);
+        }
+      },
+      xDelete: (zClass, zKey)=>{
+        const stack = pstack.pointer;
+        try {
+          const zXKey = kvvfsMakeKey(zClass,zKey);
+          if(!zXKey) return 1/*OOM*/;
+          kvvfsStorage(zClass).removeItem(wasm.cstringToJs(zXKey));
+          return 0;
+        }catch(e){
+          console.error("kvstorageDelete()",e);
+          return capi.SQLITE_IOERR;
+        }finally{
+          pstack.restore(stack);
+        }
+      }
+    }/*kvvfsImpls*/;
+    for(let k of Object.keys(kvvfsImpls)){
+      kvvfsMethods[kvvfsMethods.memberKey(k)] =
+        wasm.installFunction(
+          kvvfsMethods.memberSignature(k),
+          kvvfsImpls[k]
+        );
+    }
+    console.warn('kvvfs stuff',kvvfsMethods);
+  }/*kvvfs*/
+
   sqlite3.version = Object.assign(Object.create(null),{
     library: sqlite3.capi.sqlite3_libversion(),
     sourceId: sqlite3.capi.sqlite3_sourceid()

ext/wasm/api/sqlite3-api-prologue.js

@@ -1313,7 +1313,7 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
       // to resolve in order? We currently only have 1, so it
       // makes no difference.
       lip = lip.map((f)=>f(sqlite3).catch((e)=>{
-        console.error("An async sqlite3 initializer failed:",e);
+        console.error("Ignoring error: an async sqlite3 initializer failed:",e);
       }));
       //let p = lip.shift();
       //while(lip.length) p = p.then(lip.shift());

ext/wasm/api/sqlite3-wasm.c

@@ -13,6 +13,8 @@
 ** emcc -o sqlite3.wasm ... -I/path/to/sqlite3-c-and-h sqlite3-wasm.c
 */
 
+#define SQLITE_WASM
+
 /*
 ** Threading and file locking: JS is single-threaded. Each Worker
 ** thread is a separate instance of the JS engine so can never access
@@ -87,7 +89,7 @@
 #endif
 
 /*
-** WASM_KEEP is identical to EMSCRIPTEN_KEEPALIVE but is not
+** SQLITE_WASM_KEEP is identical to EMSCRIPTEN_KEEPALIVE but is not
 ** Emscripten-specific. It explicitly marks functions for export into
 ** the target wasm file without requiring explicit listing of those
 ** functions in Emscripten's -sEXPORTED_FUNCTIONS=... list (or
@@ -683,6 +685,14 @@ const char * sqlite3_wasm_enum_json(void){
     } _StructBinder;
 #undef CurrentStruct
 
+#define CurrentStruct sqlite3_kvvfs_methods
+    StructBinder {
+      M(xRead,"i(sspi)");
+      M(xWrite,"i(sss)");
+      M(xDelete,"i(ss)");
+      M(nKeySize,"i");
+    } _StructBinder;
+
   } out( "]"/*structs*/);
 
   out("}"/*top-level object*/);
@@ -820,6 +830,39 @@ int sqlite3_wasm_db_serialize( sqlite3* pDb, unsigned char **pOut, sqlite3_int64
   }
 }
 
+/*
+** This function is NOT part of the sqlite3 public API. It is strictly
+** for use by the sqlite project's own JS/WASM bindings.
+**
+** Allocates sqlite3KvvfsMethods.nKeySize bytes from
+** sqlite3_wasm_pstack_alloc() and returns 0 if that allocation fails,
+** else it passes that string to kvstorageMakeKey() and returns a
+** NUL-terminated pointer to that string. It is up to the caller to
+** use sqlite3_wasm_pstack_restore() to free the returned pointer.
+*/
+WASM_KEEP
+char * sqlite3_wasm_kvvfsMakeKeyOnPstack(const char *zClass,
+                                         const char *zKeyIn){
+  assert(sqlite3KvvfsMethods.nKeySize>24);
+  char *zKeyOut =
+    (char *)sqlite3_wasm_pstack_alloc(sqlite3KvvfsMethods.nKeySize);
+  if(zKeyOut){
+    kvstorageMakeKey(zClass, zKeyIn, zKeyOut);
+  }
+  return zKeyOut;
+}
+
+/*
+** This function is NOT part of the sqlite3 public API. It is strictly
+** for use by the sqlite project's own JS/WASM bindings.
+**
+** Returns the pointer to the singleton object which holds the kvvfs
+** I/O methods and associated state.
+*/
+WASM_KEEP
+sqlite3_kvvfs_methods * sqlite3_wasm_kvvfs_methods(void){
+  return &sqlite3KvvfsMethods;
+}
 
 #if defined(__EMSCRIPTEN__) && defined(SQLITE_WASM_WASMFS)
 #include <emscripten/wasmfs.h>