116 lines
3.2 KiB
JavaScript
116 lines
3.2 KiB
JavaScript
'use strict'
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const v8Util = process.electronBinding('v8_util')
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const getOwnerKey = (webContents, contextId) => {
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return `${webContents.id}-${contextId}`
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}
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class ObjectsRegistry {
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constructor () {
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this.nextId = 0
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// Stores all objects by ref-counting.
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// (id) => {object, count}
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this.storage = {}
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// Stores the IDs of objects referenced by WebContents.
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// (ownerKey) => [id]
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this.owners = {}
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}
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// Register a new object and return its assigned ID. If the object is already
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// registered then the already assigned ID would be returned.
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add (webContents, contextId, obj) {
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// Get or assign an ID to the object.
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const id = this.saveToStorage(obj)
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// Add object to the set of referenced objects.
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const ownerKey = getOwnerKey(webContents, contextId)
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let owner = this.owners[ownerKey]
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if (!owner) {
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owner = this.owners[ownerKey] = new Set()
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this.registerDeleteListener(webContents, contextId)
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}
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if (!owner.has(id)) {
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owner.add(id)
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// Increase reference count if not referenced before.
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this.storage[id].count++
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}
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return id
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}
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// Get an object according to its ID.
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get (id) {
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const pointer = this.storage[id]
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if (pointer != null) return pointer.object
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}
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// Dereference an object according to its ID.
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// Note that an object may be double-freed (cleared when page is reloaded, and
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// then garbage collected in old page).
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remove (webContents, contextId, id) {
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const ownerKey = getOwnerKey(webContents, contextId)
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const owner = this.owners[ownerKey]
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if (owner) {
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// Remove the reference in owner.
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owner.delete(id)
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// Dereference from the storage.
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this.dereference(id)
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}
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}
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// Clear all references to objects refrenced by the WebContents.
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clear (webContents, contextId) {
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const ownerKey = getOwnerKey(webContents, contextId)
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const owner = this.owners[ownerKey]
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if (!owner) return
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for (const id of owner) this.dereference(id)
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delete this.owners[ownerKey]
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}
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// Private: Saves the object into storage and assigns an ID for it.
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saveToStorage (object) {
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let id = v8Util.getHiddenValue(object, 'atomId')
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if (!id) {
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id = ++this.nextId
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this.storage[id] = {
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count: 0,
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object: object
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}
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v8Util.setHiddenValue(object, 'atomId', id)
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}
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return id
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}
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// Private: Dereference the object from store.
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dereference (id) {
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const pointer = this.storage[id]
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if (pointer == null) {
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return
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}
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pointer.count -= 1
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if (pointer.count === 0) {
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v8Util.deleteHiddenValue(pointer.object, 'atomId')
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delete this.storage[id]
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}
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}
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// Private: Clear the storage when renderer process is destroyed.
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registerDeleteListener (webContents, contextId) {
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// contextId => ${processHostId}-${contextCount}
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const processHostId = contextId.split('-')[0]
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const listener = (event, deletedProcessHostId) => {
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if (deletedProcessHostId &&
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deletedProcessHostId.toString() === processHostId) {
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webContents.removeListener('render-view-deleted', listener)
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this.clear(webContents, contextId)
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}
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}
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webContents.on('render-view-deleted', listener)
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}
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}
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module.exports = new ObjectsRegistry()
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