diff options
Diffstat (limited to 'ext')
| -rw-r--r-- | ext/wasm/api/sqlite3-opfs-async-proxy.js | 24 | ||||
| -rw-r--r-- | ext/wasm/common/whwasmutil.js | 26 |
2 files changed, 33 insertions, 17 deletions
diff --git a/ext/wasm/api/sqlite3-opfs-async-proxy.js b/ext/wasm/api/sqlite3-opfs-async-proxy.js index e671094f0..48cddd7ef 100644 --- a/ext/wasm/api/sqlite3-opfs-async-proxy.js +++ b/ext/wasm/api/sqlite3-opfs-async-proxy.js @@ -173,10 +173,10 @@ const installAsyncProxy = function(){ /** If the given file-holding object has a sync handle attached to it, - that handle is remove and asynchronously closed. Though it may + that handle is removed and asynchronously closed. Though it may sound sensible to continue work as soon as the close() returns (noting that it's asynchronous), doing so can cause operations - performed soon afterwards, e.g. a call to getSyncHandle() to fail + performed soon afterwards, e.g. a call to getSyncHandle(), to fail because they may happen out of order from the close(). OPFS does not guaranty that the actual order of operations is retained in such cases. i.e. always "await" on the result of this function. @@ -293,6 +293,20 @@ const installAsyncProxy = function(){ times. If acquisition still fails at that point it will give up and propagate the exception. Client-level code will see that as an I/O error. + + 2024-06-12: there is a rare race condition here which has been + reported a single time: + + https://sqlite.org/forum/forumpost/9ee7f5340802d600 + + What appears to be happening is that file we're waiting for a + lock on is deleted while we wait. What currently happens here is + that a locking exception is thrown but the exception type is + NotFoundError. In such cases, we very probably should attempt to + re-open/re-create the file an obtain the lock on it (noting that + there's another race condition there). That's easy to say but + creating a viable test for that condition has proven challenging + so far. */ const getSyncHandle = async (fh,opName)=>{ if(!fh.syncHandle){ @@ -674,8 +688,10 @@ const installAsyncProxy = function(){ mTimeStart('xUnlock'); let rc = 0; const fh = __openFiles[fid]; - if( state.sq3Codes.SQLITE_LOCK_NONE===lockType - && fh.syncHandle ){ + if( fh.syncHandle + && state.sq3Codes.SQLITE_LOCK_NONE===lockType + /* Note that we do not differentiate between lock types in + this VFS. We're either locked or unlocked. */ ){ wTimeStart('xUnlock'); try { await closeSyncHandle(fh) } catch(e){ diff --git a/ext/wasm/common/whwasmutil.js b/ext/wasm/common/whwasmutil.js index b8a2a8774..25400d48e 100644 --- a/ext/wasm/common/whwasmutil.js +++ b/ext/wasm/common/whwasmutil.js @@ -156,8 +156,7 @@ - 'dealloc()` must behave like C's `free()`, accepting either a pointer returned from its allocation counterpart or the values - null/0 (for which it must be a no-op). allocating N bytes of - memory and returning its pointer. In Emscripten this is + null/0 (for which it must be a no-op). In Emscripten this is conventionally made available via `Module['_free']`. APIs which require allocation routines are explicitly documented as @@ -730,22 +729,23 @@ globalThis.WhWasmUtilInstaller = function(target){ }; /** - The counterpart of peek(), this sets a numeric value at - the given WASM heap address, using the type to define how many - bytes are written. Throws if given an invalid type. See - peek() for details about the type argument. If the 3rd - argument ends with `*` then it is treated as a pointer type and - this function behaves as if the 3rd argument were `i32`. + The counterpart of peek(), this sets a numeric value at the given + WASM heap address, using the 3rd argument to define how many + bytes are written. Throws if given an invalid type. See peek() + for details about the `type` argument. If the 3rd argument ends + with `*` then it is treated as a pointer type and this function + behaves as if the 3rd argument were `i32`. If the first argument is an array, it is treated like a list of pointers and the given value is written to each one. - Returns `this`. (Prior to 2022-12-09 it returns this function.) + Returns `this`. (Prior to 2022-12-09 it returned this function.) - ACHTUNG: calling this often, e.g. in a loop, can have a noticably - painful impact on performance. Rather than doing so, use - heapForSize() to fetch the heap object and assign directly to it - or use the heap's set() method. + ACHTUNG: calling this often, e.g. in a loop to populate a large + chunk of memory, can have a noticably painful impact on + performance. Rather than doing so, use heapForSize() to fetch the + heap object and assign directly to it or use the heap's set() + method. */ target.poke = function(ptr, value, type='i8'){ if (type.endsWith('*')) type = ptrIR; |