df8e617772
This is a reland of bc33f5aeba
Original change's description:
> [arraybuffer] Rearchitect backing store ownership
>
> This CL completely rearchitects the ownership of array buffer backing stores,
> consolidating ownership into a {BackingStore} C++ object that is tracked
> throughout V8 using unique_ptr and shared_ptr where appropriate.
>
> Overall, lifetime management is simpler and more explicit. The numerous
> ways that array buffers were initialized have been streamlined to one
> Attach() method on JSArrayBuffer. The array buffer tracker in the
> GC implementation now manages std::shared_ptr<BackingStore> pointers,
> and the construction and destruction of the BackingStore object itself
> handles the underlying page or embedder-allocated memory.
>
> The embedder API remains unchanged for now. We use the
> v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> keep the backing store alive properly, even in the case of aliases
> from live heap objects. Thus the embedder has a lower chance of making
> a mistake. Long-term, we should move the embedder to a model where they
> manage backing stores using shared_ptr to an opaque backing store object.
R=mlippautz@chromium.org
BUG=v8:9380,v8:9221,chromium:986318
TBR=ulan@chromium.org
Change-Id: I6c49e2425029b5664ef1c68dab8b5146f4ed0ff2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1719191
Reviewed-by: Ben Titzer <titzer@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63007}
42 lines
945 B
JavaScript
42 lines
945 B
JavaScript
// Copyright 2019 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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let kPageSize = 65536;
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function allocMems(count, initial, maximum) {
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print(`alloc ${count}`);
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let result = [];
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for (let i = 0; i < count; i++) {
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print(` memory #${i} (initial=${initial}, maximum=${maximum})...`);
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result.push(new WebAssembly.Memory({initial: initial, maximum: maximum}));
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}
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return result;
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}
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function check(mems, initial) {
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for (m of mems) {
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assertEquals(initial * kPageSize, m.buffer.byteLength);
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}
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}
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function test(count, initial, maximum) {
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let mems = allocMems(count, initial, maximum);
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check(mems, initial);
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}
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test(1, 1, 1);
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test(1, 1, 2);
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test(1, 1, 3);
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test(1, 1, 4);
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test(2, 1, 1);
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test(2, 1, 2);
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test(2, 1, 3);
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test(2, 1, 4);
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test(1, 1, undefined);
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test(2, 1, undefined);
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test(3, 1, undefined);
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test(4, 1, undefined);
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