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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
commit | 36d22d82aa202bb199967e9512281e9a53db42c9 (patch) | |
tree | 105e8c98ddea1c1e4784a60a5a6410fa416be2de /devtools/shared/network-observer/ChannelMap.sys.mjs | |
parent | Initial commit. (diff) | |
download | firefox-esr-upstream.tar.xz firefox-esr-upstream.zip |
Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'devtools/shared/network-observer/ChannelMap.sys.mjs')
-rw-r--r-- | devtools/shared/network-observer/ChannelMap.sys.mjs | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/devtools/shared/network-observer/ChannelMap.sys.mjs b/devtools/shared/network-observer/ChannelMap.sys.mjs new file mode 100644 index 0000000000..3c54b1171a --- /dev/null +++ b/devtools/shared/network-observer/ChannelMap.sys.mjs @@ -0,0 +1,129 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +/** + * FinalizationRegistry callback, see + * https://searchfox.org/mozilla-central/source/js/src/builtin/FinalizationRegistryObject.h + * + * Will be invoked when the channel corresponding to the weak reference is + * "destroyed", at which point we can cleanup the corresponding entry in our + * regular map. + */ +function deleteIdFromRefMap({ refMap, id }) { + refMap.delete(id); +} + +/** + * This object implements iterable weak map for HTTP channels tracked by + * the network observer. + * + * We can't use Map() for storing HTTP channel references since we don't + * know when we should remove the entry in it (it's wrong to do it in + * 'onTransactionClose' since it doesn't have to be the last platform + * notification for a given channel). We want the map to auto update + * when the channel is garbage collected. + * + * We can't use WeakMap() since searching for a value by the channel object + * isn't reliable (there might be different objects representing the same + * channel). We need to search by channel ID, but ID can't be used as key + * in WeakMap(). + * + * So, this custom map solves aforementioned issues. + */ +export class ChannelMap { + #finalizationRegistry; + #refMap; + #weakMap; + + constructor() { + // See https://searchfox.org/mozilla-central/source/js/src/builtin/FinalizationRegistryObject.h + this.#finalizationRegistry = new FinalizationRegistry(deleteIdFromRefMap); + + // Map of channel id to a channel weak reference. + this.#refMap = new Map(); + + /** + * WeakMap from nsIChannel instances to objects which encapsulate ChannelMap + * values with the following structure: + * @property {Object} value + * The actual value stored in this ChannelMap entry, which should relate + * to this channel. + * @property {WeakRef} ref + * Weak reference for the channel object which is the key of the entry. + */ + this.#weakMap = new WeakMap(); + } + + /** + * Remove all entries from the ChannelMap. + */ + clear() { + this.#refMap.clear(); + } + + /** + * Delete the entry for the provided channel from the underlying maps, if any. + * Note that this will only delete entries which were set for the exact same + * nsIChannel object, and will not attempt to look up entries by channel id. + * + * @param {nsIChannel} channel + * The key to delete from the ChannelMap. + * + * @return {boolean} + * True if an entry was deleted, false otherwise. + */ + delete(channel) { + const entry = this.#weakMap.get(channel); + if (!entry) { + return false; + } + + this.#weakMap.delete(channel); + this.#refMap.delete(channel.channelId); + this.#finalizationRegistry.unregister(entry.ref); + return true; + } + + /** + * Retrieve a value stored in the ChannelMap by the provided channel. + * + * @param {nsIChannel} channel + * The key to delete from the ChannelMap. + * + * @return {Object|null} + * The value held for the provided channel. + * Null if the channel did not match any known key. + */ + get(channel) { + const ref = this.#refMap.get(channel.channelId); + const key = ref ? ref.deref() : null; + if (!key) { + return null; + } + const channelInfo = this.#weakMap.get(key); + return channelInfo ? channelInfo.value : null; + } + + /** + * Adds or updates an entry in the ChannelMap for the provided channel. + * + * @param {nsIChannel} channel + * The key of the entry to add or update. + * @param {Object} value + * The value to add or update. + */ + set(channel, value) { + const ref = new WeakRef(channel); + this.#weakMap.set(channel, { value, ref }); + this.#refMap.set(channel.channelId, ref); + this.#finalizationRegistry.register( + channel, + { + refMap: this.#refMap, + id: channel.channelId, + }, + ref + ); + } +} |