wasm: correct a memleak caused by a shadowed var in the previous checkin. Add a stack-like allocator, sqlite3.capi.wasm.pstack, as a faster way of managing short-lived pointers (like the one which got shadowed).
FossilOrigin-Name: 1fa019c88deac6b6e5155b620bdab1d7145846290daafb9adbefcf4f0fe542cf
This commit is contained in:
stephan
parent
32781427d7
commit
3afad4d432
@ -738,30 +738,92 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
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["sqlite3_wasm_vfs_unlink", "int", "string"]
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];
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/**
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sqlite3.capi.wasm.pstack (pseudo-stack) holds a special-case
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stack-style allocator intended only for use with _small_ data of
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not more than (in total) a few kb in size, managed as if it were
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stack-based.
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It has only a single intended usage:
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```
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const stackPos = pstack.pointer;
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try{
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const ptr = pstack.alloc(8);
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// ==> pstack.pointer === ptr
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const otherPtr = pstack.alloc(8);
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// ==> pstack.pointer === otherPtr
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...
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}finally{
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pstack.restore(stackPos);
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// ==> pstack.pointer === stackPos
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}
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```
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This allocator is much faster than a general-purpose one but is
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limited to usage patterns like the one shown above.
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It operates from a static range of memory which lives outside of
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space managed by Emscripten's stack-management, so does not
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collide with Emscripten-provided stack allocation APIs. The
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memory lives in the WASM heap and can be used with routines such
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as wasm.setMemValue() and any wasm.heap8u().slice().
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*/
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capi.wasm.pstack = Object.assign(Object.create(null),{
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/**
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Sets the current ppstack position to the given pointer.
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Results are undefined if the passed-in value did not come from
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this.pointer.
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*/
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restore: capi.wasm.exports.sqlite3_wasm_pstack_restore,
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/**
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Attempts to allocate the given number of bytes from the
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pstack. On success, it zeroes out a block of memory of the
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given size, adjusts the pstack pointer, and returns a pointer
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to the memory. On error, returns 0. The memory must eventually
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be released using restore().
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This method always adjusts the given value to be a multiple
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of 8 in order to keep alignment guarantees.
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*/
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alloc: capi.wasm.exports.sqlite3_wasm_pstack_alloc
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});
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/**
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sqlite3.capi.wasm.pstack.pointer resolves to the current pstack
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position pointer. This value is intended _only_ to be passed to restore().
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*/
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Object.defineProperty(capi.wasm.pstack, 'pointer', {
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configurable: false, iterable: true, writeable: false,
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get: capi.wasm.exports.sqlite3_wasm_pstack_ptr
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//Whether or not a setter as an alternative to restore() is
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//clearer or would just lead to confusion is unclear.
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//set: capi.wasm.exports.sqlite3_wasm_pstack_restore
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});
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/**
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sqlite3.capi.wasm.pstack.remaining resolves to the amount of
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space remaining in the pstack.
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*/
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Object.defineProperty(capi.wasm.pstack, 'remaining', {
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configurable: false, iterable: true, writeable: false,
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get: capi.wasm.exports.sqlite3_wasm_pstack_remaining
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});
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/** State for sqlite3_wasmfs_opfs_dir(). */
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let __persistentDir = undefined;
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/**
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An experiment. Do not use in client code.
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If the wasm environment has a persistent storage directory,
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its path is returned by this function. If it does not then
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it returns "" (noting that "" is a falsy value).
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If the wasm environment has a WASMFS/OPFS-backed persistent
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storage directory, its path is returned by this function. If it
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does not then it returns "" (noting that "" is a falsy value).
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The first time this is called, this function inspects the current
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environment to determine whether persistence filesystem support
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is available and, if it is, enables it (if needed).
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environment to determine whether persistence support is available
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and, if it is, enables it (if needed).
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This function currently only recognizes the WASMFS/OPFS storage
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combination. "Plain" OPFS is provided via a separate VFS which
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is optionally be installed via sqlite3.asyncPostInit().
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TODOs and caveats:
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- If persistent storage is available at the root of the virtual
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filesystem, this interface cannot currently distinguish that
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from the lack of persistence. That can (in the mean time)
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happen when using the JS-native "opfs" VFS, as opposed to the
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WASMFS/OPFS combination.
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combination and its path refers to storage rooted in the
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Emscripten-managed virtual filesystem.
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*/
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capi.sqlite3_wasmfs_opfs_dir = function(){
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if(undefined !== __persistentDir) return __persistentDir;
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@ -879,10 +941,10 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
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if(!pDb) toss('Invalid sqlite3* argument.');
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const wasm = capi.wasm;
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if(!wasm.bigIntEnabled) toss('BigInt64 support is not enabled.');
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const scope = wasm.scopedAllocPush();
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const stack = wasm.pstack.pointer();
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let pOut;
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try{
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const pSize = wasm.scopedAlloc(8/*i64*/ + wasm.ptrSizeof);
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const pSize = wasm.pstack.alloc(8/*i64*/ + wasm.ptrSizeof);
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const ppOut = pSize + 8;
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/**
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Maintenance reminder, since this cost a full hour of grief
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@ -891,8 +953,6 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
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export reads a garbage size because it's not on an 8-byte
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memory boundary!
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*/
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wasm.setPtrValue(ppOut, 0);
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wasm.setMemValue(pSize, 0, 'i64');
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let rc = wasm.exports.sqlite3_wasm_db_serialize(
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pDb, ppOut, pSize, 0
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);
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@ -900,7 +960,7 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
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toss("Database serialization failed with code",
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sqlite3.capi.sqlite3_web_rc_str(rc));
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}
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const pOut = wasm.getPtrValue(ppOut);
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pOut = wasm.getPtrValue(ppOut);
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const nOut = wasm.getMemValue(pSize, 'i64');
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rc = nOut
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? wasm.heap8u().slice(pOut, pOut + Number(nOut))
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@ -911,7 +971,7 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
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throw w;
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}finally{
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if(pOut) wasm.exports.sqlite3_free(pOut);
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wasm.scopedAllocPop(scope);
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wasm.pstack.restore(stack);
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}
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};
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@ -56,6 +56,7 @@
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# define SQLITE_THREADSAFE 0
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#endif
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#include <assert.h>
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#include "sqlite3.c" /* yes, .c instead of .h. */
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/*
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@ -85,6 +86,110 @@
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// See also:
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//__attribute__((export_name("theExportedName"), used, visibility("default")))
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#if 0
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/*
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** An EXPERIMENT in implementing a stack-based allocator analog to
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** Emscripten's stackSave(), stackAlloc(), stackRestore().
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** Unfortunately, this cannot work together with Emscripten because
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** Emscripten defines its own native one and we'd stomp on each
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** other's memory. Other than that complication, basic tests show it
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** to work just fine.
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**
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** Another option is to malloc() a chunk of our own and call that our
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** "stack".
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*/
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WASM_KEEP void * sqlite3_wasm_stack_end(void){
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extern void __heap_base
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/* see https://stackoverflow.com/questions/10038964 */;
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return &__heap_base;
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}
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WASM_KEEP void * sqlite3_wasm_stack_begin(void){
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extern void __data_end;
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return &__data_end;
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}
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static void * sq3StackPtr = 0;
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WASM_KEEP void * sqlite3_wasm_stack_ptr(void){
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if(!sq3StackPtr) sq3StackPtr = sqlite3_wasm_stack_end();
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return sq3StackPtr;
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}
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WASM_KEEP void sqlite3_wasm_stack_restore(void * p){
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sq3StackPtr = p;
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}
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WASM_KEEP void * sqlite3_wasm_stack_alloc(int n){
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if(n<=0) return 0;
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n = (n + 7) & ~7 /* align to 8-byte boundary */;
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unsigned char * const p = (unsigned char *)sqlite3_wasm_stack_ptr();
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unsigned const char * const b = (unsigned const char *)sqlite3_wasm_stack_begin();
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if(b + n >= p || b + n < b/*overflow*/) return 0;
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return sq3StackPtr = p - n;
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}
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#endif /* stack allocator experiment */
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/*
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** State for the "pseudo-stack" allocator implemented in
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** sqlite3_wasm_pstack_xyz(). In order to avoid colliding with
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** Emscripten-controled stack space, it carves out a bit of stack
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** memory to use for that purpose. This memory ends up in the
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** WASM-managed memory, such that routines which manipulate the wasm
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** heap can also be used to manipulate this memory.
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*/
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static unsigned char PStack_mem[512 * 8] = {0};
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static struct {
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unsigned char const * pBegin; /* Start (inclusive) of memory range */
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unsigned char const * pEnd; /* One-after-the-end of memory range */
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unsigned char * pPos; /* Current "stack pointer" */
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} PStack = {
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&PStack_mem[0],
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&PStack_mem[0] + sizeof(PStack_mem),
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&PStack_mem[0] + sizeof(PStack_mem)
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};
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/*
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** Returns the current pstack position.
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*/
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WASM_KEEP void * sqlite3_wasm_pstack_ptr(void){
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return PStack.pPos;
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}
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/*
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** Sets the pstack position poitner to p. Results are undefined if the
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** given value did not come from sqlite3_wasm_pstack_ptr().
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*/
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WASM_KEEP void sqlite3_wasm_pstack_restore(unsigned char * p){
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assert(p>=PStack.pBegin && p<=PStack.pEnd && p>=PStack.pPos);
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assert(0==(p & 0x7));
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if(p>=PStack.pBegin && p<=PStack.pEnd /*&& p>=PStack.pPos*/){
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PStack.pPos = p;
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}
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}
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/*
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** Allocate and zero out n bytes from the pstack. Returns a pointer to
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** the memory on success, 0 on error (including a negative n value). n
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** is always adjusted to be a multiple of 8 and returned memory is
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** always zeroed out before returning (because this keeps the client
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** JS code from having to do so, and most uses of the pstack will
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** call for doing so).
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*/
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WASM_KEEP void * sqlite3_wasm_pstack_alloc(int n){
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if( n<=0 ) return 0;
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//if( n & 0x7 ) n += 8 - (n & 0x7) /* align to 8-byte boundary */;
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n = (n + 7) & ~7 /* align to 8-byte boundary */;
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unsigned char * const p = PStack.pPos;
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unsigned const char * const b = PStack.pBegin;
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if( b + n > p || b + n <= b/*overflow*/ ) return 0;
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memset((PStack.pPos = p - n), 0, (unsigned int)n);
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return PStack.pPos;
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}
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/*
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** Return the number of bytes left which can be
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** sqlite3_wasm_pstack_alloc()'d.
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*/
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WASM_KEEP int sqlite3_wasm_pstack_remaining(void){
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assert(PStack.pPos >= PStack.pBegin);
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assert(PStack.pPos <= PStack.pEnd);
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return (int)(PStack.pPos - PStack.pBegin);
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}
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/*
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** This function is NOT part of the sqlite3 public API. It is strictly
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** for use by the sqlite project's own JS/WASM bindings.
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@ -875,7 +875,7 @@
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log("cstrncpy()...");
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{
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w.scopedAllocPush();
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const scope = w.scopedAllocPush();
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try {
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let cStr = w.scopedAllocCString("hello");
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const n = w.cstrlen(cStr);
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@ -892,7 +892,7 @@
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assert(chr('!') === w.getMemValue(cpy+2)).
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assert(chr('l') === w.getMemValue(cpy+3));
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}finally{
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w.scopedAllocPop();
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w.scopedAllocPop(scope);
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}
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}
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@ -1024,6 +1024,38 @@
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}
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}/*testWasmUtil()*/;
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/**
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Tests for sqlite3.capi.wasm.pstack().
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*/
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const testPstack = function(db,sqlite3){
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const w = sqlite3.capi.wasm, P = w.pstack;
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const stack = P.pointer;
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T.assert(0===stack % 8 /* must be 8-byte aligned */);
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try{
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const quota = P.remaining;
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log("pstack quota",quota);
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T.assert(quota >= 4096)
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.assert(0 === P.alloc(0))
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.assert(0 === P.alloc(-1));
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let p1 = P.alloc(12);
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T.assert(p1 === stack - 16/*8-byte aligned*/)
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.assert(P.pointer === p1);
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let p2 = P.alloc(7);
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T.assert(p2 === p1-8/*8-byte aligned, stack grows downwards*/)
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.assert(0 === P.alloc(quota))
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.assert(24 === stack - p2)
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.assert(P.pointer === p2);
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let n = quota - (stack - p2);
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let p3 = P.alloc(n);
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T.assert(p3 === stack-quota)
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.assert(0 === P.alloc(1));
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}finally{
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P.restore(stack);
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T.assert(P.pointer === stack);
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}
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}/*testPstack()*/;
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const clearKvvfs = function(){
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const sz = sqlite3.capi.sqlite3_web_kvvfs_size();
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const n = sqlite3.capi.sqlite3_web_kvvfs_clear('');
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@ -1089,7 +1121,7 @@
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[
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testWasmUtil, testBasicSanity, testUDF,
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testAttach, testIntPtr, testStructStuff,
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testSqliteStructs
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testSqliteStructs, testPstack
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].forEach((f)=>{
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const t = T.counter, n = performance.now();
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logHtml(banner1,"Running",f.name+"()...");
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16
manifest
16
manifest
@ -1,5 +1,5 @@
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C Fiddle:\sfix\smakefile\sdependency\sissue\sand\sduplicate\sinclusion\sof\spost-js.js.\sReimplement\sdb\sexport\susing\ssqlite3_serialize().
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D 2022-10-01T16:01:41.242
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C wasm:\scorrect\sa\smemleak\scaused\sby\sa\sshadowed\svar\sin\sthe\sprevious\scheckin.\sAdd\sa\sstack-like\sallocator,\ssqlite3.capi.wasm.pstack,\sas\sa\sfaster\sway\sof\smanaging\sshort-lived\spointers\s(like\sthe\sone\swhich\sgot\sshadowed).
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D 2022-10-01T18:47:42.149
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F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
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F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
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F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
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@ -488,10 +488,10 @@ F ext/wasm/api/sqlite3-api-cleanup.js 5d22d1d3818ecacb23bfa223d5970cd0617d8cdbb4
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F ext/wasm/api/sqlite3-api-glue.js b15a51b88aaa472d36bf82d5123dbfdafe8ddf6ca75fba934510e4a20bbe4adb
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F ext/wasm/api/sqlite3-api-oo1.js 9caed0757a5e039ed92467e827fd3ca347fa08f19fe086fcbdd14a4ebe9c2f01
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F ext/wasm/api/sqlite3-api-opfs.js 1b097808b7b081b0f0700cf97d49ef19760e401706168edff9cd45cf9169f541
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F ext/wasm/api/sqlite3-api-prologue.js d7904da82691f68b9ffb081c072cf4725716154284a63447f2d1dce40ab4b85f
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F ext/wasm/api/sqlite3-api-prologue.js 895b5f9ee425b8ba4a5fc5c85f144da9e2b785fea9226830f068d5c3b71e0fba
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F ext/wasm/api/sqlite3-api-worker1.js 7f4f46cb6b512a48572d7567233896e6a9c46570c44bdc3d13419730c7c221c8
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F ext/wasm/api/sqlite3-wasi.h 25356084cfe0d40458a902afb465df8c21fc4152c1d0a59b563a3fba59a068f9
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F ext/wasm/api/sqlite3-wasm.c 61c6bf8404a07f3d5f2861fbc1d3596474cecfc38801fb3a38c560fe847f79a5
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F ext/wasm/api/sqlite3-wasm.c 43216a5266780f5f6ca3972684be5cd9113b624e43a5f5923c06a0c386e65857
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F ext/wasm/batch-runner.html c363032aba7a525920f61f8be112a29459f73f07e46f0ba3b7730081a617826e
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F ext/wasm/batch-runner.js ce92650a6681586c89bef26ceae96674a55ca5a9727815202ca62e1a00ff5015
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F ext/wasm/common/SqliteTestUtil.js 647bf014bd30bdd870a7e9001e251d12fc1c9ec9ce176a1004b838a4b33c5c05
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@ -530,7 +530,7 @@ F ext/wasm/test-opfs-vfs.js a59ff9210b17d46b0c6fbf6a0ba60143c033327865f2e556e14f
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F ext/wasm/testing-worker1-promiser.html 6eaec6e04a56cf24cf4fa8ef49d78ce8905dde1354235c9125dca6885f7ce893
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F ext/wasm/testing-worker1-promiser.js bd788e33c1807e0a6dda9c9a9d784bd3350ca49c9dd8ae2cc8719b506b6e013e
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F ext/wasm/testing1.html 50575755e43232dbe4c2f97c9086b3118eb91ec2ee1fae931e6d7669fb17fcae
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F ext/wasm/testing1.js 5584e9b68f797dbc0f6161360f2c6840169533813d92c74d355a3e78dd5bb539
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F ext/wasm/testing1.js 419e029ee4ae3cf98dd4c20aebdb111afe743b54ed8856e5f59775c3241fd21f
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F ext/wasm/testing2.html a66951c38137ff1d687df79466351f3c734fa9c6d9cce71d3cf97c291b2167e3
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F ext/wasm/testing2.js 88f40ef3cd8201bdadd120a711c36bbf0ce56cc0eab1d5e7debb71fed7822494
|
||||
F ext/wasm/wasmfs.make 3cce1820006196de140f90f2da4b4ea657083fb5bfee7d125be43f7a85748c8f
|
||||
@ -2029,8 +2029,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
|
||||
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
|
||||
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
|
||||
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
|
||||
P 64ebcbe41615a6d7776597564105ea7638e4a9095a764ea558c2620640429cf8
|
||||
R 624d71ac921985ea3965d7f2eda6af5a
|
||||
P 29db7de79232c21d19b91bb0fc253114e02e21dd9bf90619453dbe72a4c8bf7f
|
||||
R bd74fd06e0648815273bfbe7fab3eb12
|
||||
U stephan
|
||||
Z 9261b853936f36a4eb842018d682a85c
|
||||
Z 599287064c24d1dab9b272142121f171
|
||||
# Remove this line to create a well-formed Fossil manifest.
|
||||
|
||||
@ -1 +1 @@
|
||||
29db7de79232c21d19b91bb0fc253114e02e21dd9bf90619453dbe72a4c8bf7f
|
||||
1fa019c88deac6b6e5155b620bdab1d7145846290daafb9adbefcf4f0fe542cf
|
||||
Loading…
Reference in New Issue
Block a user