Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

cheaper getIterator #13154

Merged
merged 1 commit into from
Apr 19, 2021
Merged

cheaper getIterator #13154

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Jump to
Jump to file
Failed to load files.
Diff view
Diff view
144 changes: 87 additions & 57 deletions lib/FileSystemInfo.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,92 @@ const DONE_ITERATOR_RESULT = new Set().keys().next();
// Tsh = Timestamp + Hash
// Tshs = Timestamp + Hash combinations

class SnapshotIterator {
constructor(next) {
this.next = next;
}
}

class SnapshotIterable {
constructor(snapshot, getMaps) {
this.snapshot = snapshot;
this.getMaps = getMaps;
}

[Symbol.iterator]() {
let state = 0;
/** @type {IterableIterator<string>} */
let it;
/** @type {(Snapshot) => (Map<string, any> | Set<string>)[]} */
let getMaps;
/** @type {(Map<string, any> | Set<string>)[]} */
let maps;
/** @type {Snapshot} */
let snapshot;
let queue;
return new SnapshotIterator(() => {
for (;;) {
switch (state) {
case 0:
snapshot = this.snapshot;
getMaps = this.getMaps;
maps = getMaps(snapshot);
state = 1;
/* falls through */
case 1:
if (maps.length > 0) {
const map = maps.pop();
if (map !== undefined) {
it = map.keys();
state = 2;
} else {
break;
}
} else {
state = 3;
break;
}
/* falls through */
case 2: {
const result = it.next();
if (!result.done) return result;
state = 1;
break;
}
case 3: {
const children = snapshot.children;
if (children !== undefined) {
if (children.size === 1) {
// shortcut for a single child
// avoids allocation of queue
for (const child of children) snapshot = child;
maps = getMaps(snapshot);
state = 1;
break;
}
if (queue === undefined) queue = [];
for (const child of children) {
queue.push(child);
}
}
if (queue !== undefined && queue.length > 0) {
snapshot = queue.pop();
maps = getMaps(snapshot);
state = 1;
break;
} else {
state = 4;
}
}
/* falls through */
case 4:
return DONE_ITERATOR_RESULT;
}
}
});
}
}

class Snapshot {
constructor() {
this._flags = 0;
Expand Down Expand Up @@ -283,63 +369,7 @@ class Snapshot {
* @returns {Iterable<string>} iterable
*/
_createIterable(getMaps) {
let snapshot = this;
return {
[Symbol.iterator]() {
let state = 0;
/** @type {IterableIterator<string>} */
let it;
let maps = getMaps(snapshot);
const queue = [];
return {
next() {
for (;;) {
switch (state) {
case 0:
if (maps.length > 0) {
const map = maps.pop();
if (map !== undefined) {
it = map.keys();
state = 1;
} else {
break;
}
} else {
state = 2;
break;
}
/* falls through */
case 1: {
const result = it.next();
if (!result.done) return result;
state = 0;
break;
}
case 2: {
const children = snapshot.children;
if (children !== undefined) {
for (const child of children) {
queue.push(child);
}
}
if (queue.length > 0) {
snapshot = queue.pop();
maps = getMaps(snapshot);
state = 0;
break;
} else {
state = 3;
}
}
/* falls through */
case 3:
return DONE_ITERATOR_RESULT;
}
}
}
};
}
};
return new SnapshotIterable(this, getMaps);
}

/**
Expand Down