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Add sqlite3.wasm.alloc.impl() as a "public back door" into the low-level non-throwing allocator. Correct sqlite3.WasmAllocError constructor to behave like its usages expect it to and add tests for that.

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FossilOrigin-Name: cea8bf9a144d842c4755c3130273524926e8c4831d7f21c4e34d4e8c74109c8c
This commit is contained in:
stephan
2022-11-07 13:06:20 +00:00
parent da01757870
commit 690d4c545d
4 changed files with 65 additions and 25 deletions
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58
ext/wasm/api/sqlite3-api-prologue.js
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@ -399,8 +399,22 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
exceptions.
*/
class WasmAllocError extends Error {
/**
If called with 2 arguments and the 2nd one is an object, it
behaves like the Error constructor, else it concatenates all
arguments together with a single space between each to
construct an error message string. As a special case, if
called with no arguments then it uses a default error
message.
*/
constructor(...args){
super(...args);
if(2===args.length && 'object'===typeof args){
super(...args);
}else if(args.length){
super(args.join(' '));
}else{
super("Allocation failed.");
}
this.name = 'WasmAllocError';
}
};
@ -710,21 +724,33 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
API NOT throw and must instead return SQLITE_NOMEM (or
equivalent, depending on the context).
That said, very few cases in the API can result in
Very few cases in the sqlite3 JS APIs can result in
client-defined functions propagating exceptions via the C-style
API. Most notably, this applies ot User-defined SQL Functions
(UDFs) registered via sqlite3_create_function_v2(). For that
specific case it is recommended that all UDF creation be
funneled through a utility function and that a wrapper function
be added around the UDF which catches any exception and sets
the error state to OOM. (The overall complexity of registering
UDFs essentially requires a helper for doing so!)
API. Most notably, this applies to WASM-bound JS functions
which are created directly by clients and passed on _as WASM
function pointers_ to functions such as
sqlite3_create_function_v2(). Such bindings created
transparently by this API will automatically use wrappers which
catch exceptions and convert them to appropriate error codes.
For cases where non-throwing allocation is required, use
sqlite3.wasm.alloc.impl(), which is direct binding of the
underlying C-level allocator.
Design note: this function is not named "malloc" primarily
because Emscripten uses that name and we wanted to avoid any
confusion early on in this code's development, when it still
had close ties to Emscripten's glue code.
*/
alloc: undefined/*installed later*/,
/**
The API's one single point of access to the WASM-side memory
deallocator. Works like free(3) (and is likely bound to
free()).
Design note: this function is not named "free" for the same
reason that this.alloc() is not called this.malloc().
*/
dealloc: undefined/*installed later*/
@ -752,7 +778,9 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
wasm.allocFromTypedArray = function(srcTypedArray){
affirmBindableTypedArray(srcTypedArray);
const pRet = wasm.alloc(srcTypedArray.byteLength || 1);
wasm.heapForSize(srcTypedArray.constructor).set(srcTypedArray.byteLength ? srcTypedArray : [0], pRet);
wasm.heapForSize(srcTypedArray.constructor).set(
srcTypedArray.byteLength ? srcTypedArray : [0], pRet
);
return pRet;
};
@ -763,13 +791,13 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
if(!(f instanceof Function)) toss3("Missing required exports[",key,"] function.");
}
wasm.alloc = function(n){
const m = wasm.exports[keyAlloc](n);
if(!m) throw new WasmAllocError("Failed to allocate "+n+" bytes.");
wasm.alloc = function f(n){
const m = f.impl(n);
if(!m) throw new WasmAllocError("Failed to allocate",n," bytes.");
return m;
};
wasm.dealloc = (m)=>wasm.exports[keyDealloc](m);
wasm.alloc.impl = wasm.exports[keyAlloc];
wasm.dealloc = wasm.exports[keyDealloc];
/**
Reports info about compile-time options using