@electron/remote
Version:
[](https://circleci.com/gh/electron/remote/tree/main) [](https://npmjs.org/package/@electron/remote
118 lines (117 loc) • 4.44 kB
JavaScript
"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
const getOwnerKey = (webContents, contextId) => {
return `${webContents.id}-${contextId}`;
};
class ObjectsRegistry {
constructor() {
this.nextId = 0;
// Stores all objects by ref-counting.
// (id) => {object, count}
this.storage = {};
// Stores the IDs + refCounts of objects referenced by WebContents.
// (ownerKey) => { id: refCount }
this.owners = {};
this.electronIds = new WeakMap();
}
// Register a new object and return its assigned ID. If the object is already
// registered then the already assigned ID would be returned.
add(webContents, contextId, obj) {
// Get or assign an ID to the object.
const id = this.saveToStorage(obj);
// Add object to the set of referenced objects.
const ownerKey = getOwnerKey(webContents, contextId);
let owner = this.owners[ownerKey];
if (!owner) {
owner = this.owners[ownerKey] = new Map();
this.registerDeleteListener(webContents, contextId);
}
if (!owner.has(id)) {
owner.set(id, 0);
// Increase reference count if not referenced before.
this.storage[id].count++;
}
owner.set(id, owner.get(id) + 1);
return id;
}
// Get an object according to its ID.
get(id) {
const pointer = this.storage[id];
if (pointer != null)
return pointer.object;
}
// Dereference an object according to its ID.
// Note that an object may be double-freed (cleared when page is reloaded, and
// then garbage collected in old page).
remove(webContents, contextId, id) {
const ownerKey = getOwnerKey(webContents, contextId);
const owner = this.owners[ownerKey];
if (owner && owner.has(id)) {
const newRefCount = owner.get(id) - 1;
// Only completely remove if the number of references GCed in the
// renderer is the same as the number of references we sent them
if (newRefCount <= 0) {
// Remove the reference in owner.
owner.delete(id);
// Dereference from the storage.
this.dereference(id);
}
else {
owner.set(id, newRefCount);
}
}
}
// Clear all references to objects refrenced by the WebContents.
clear(webContents, contextId) {
const ownerKey = getOwnerKey(webContents, contextId);
const owner = this.owners[ownerKey];
if (!owner)
return;
for (const id of owner.keys())
this.dereference(id);
delete this.owners[ownerKey];
}
// Saves the object into storage and assigns an ID for it.
saveToStorage(object) {
let id = this.electronIds.get(object);
if (!id) {
id = ++this.nextId;
this.storage[id] = {
count: 0,
object: object
};
this.electronIds.set(object, id);
}
return id;
}
// Dereference the object from store.
dereference(id) {
const pointer = this.storage[id];
if (pointer == null) {
return;
}
pointer.count -= 1;
if (pointer.count === 0) {
this.electronIds.delete(pointer.object);
delete this.storage[id];
}
}
// Clear the storage when renderer process is destroyed.
registerDeleteListener(webContents, contextId) {
// contextId => ${processHostId}-${contextCount}
const processHostId = contextId.split('-')[0];
const listener = (_, deletedProcessHostId) => {
if (deletedProcessHostId &&
deletedProcessHostId.toString() === processHostId) {
webContents.removeListener('render-view-deleted', listener);
this.clear(webContents, contextId);
}
};
// Note that the "render-view-deleted" event may not be emitted on time when
// the renderer process get destroyed because of navigation, we rely on the
// renderer process to send "ELECTRON_BROWSER_CONTEXT_RELEASE" message to
// guard this situation.
webContents.on('render-view-deleted', listener);
}
}
exports.default = new ObjectsRegistry();