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denoland-deno/cli/rt/10_dispatch_minimal.js
2020-08-07 16:47:18 -04:00

116 lines
3 KiB
JavaScript

// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
((window) => {
const core = window.Deno.core;
const util = window.__bootstrap.util;
// Using an object without a prototype because `Map` was causing GC problems.
const promiseTableMin = Object.create(null);
// Note it's important that promiseId starts at 1 instead of 0, because sync
// messages are indicated with promiseId 0. If we ever add wrap around logic for
// overflows, this should be taken into account.
let _nextPromiseId = 1;
const decoder = new TextDecoder();
function nextPromiseId() {
return _nextPromiseId++;
}
function recordFromBufMinimal(ui8) {
const header = ui8.subarray(0, 12);
const buf32 = new Int32Array(
header.buffer,
header.byteOffset,
header.byteLength / 4,
);
const promiseId = buf32[0];
const arg = buf32[1];
const result = buf32[2];
let err;
if (arg < 0) {
const codeLen = result;
const codeAndMessage = decoder.decode(ui8.subarray(12));
const errorCode = codeAndMessage.slice(0, codeLen);
const message = codeAndMessage.slice(codeLen);
err = { kind: errorCode, message };
} else if (ui8.length != 12) {
throw new TypeError("Malformed response message");
}
return {
promiseId,
arg,
result,
err,
};
}
function unwrapResponse(res) {
if (res.err != null) {
throw new (core.getErrorClass(res.err.kind))(res.err.message);
}
return res.result;
}
const scratch32 = new Int32Array(3);
const scratchBytes = new Uint8Array(
scratch32.buffer,
scratch32.byteOffset,
scratch32.byteLength,
);
util.assert(scratchBytes.byteLength === scratch32.length * 4);
function asyncMsgFromRust(ui8) {
const record = recordFromBufMinimal(ui8);
const { promiseId } = record;
const promise = promiseTableMin[promiseId];
delete promiseTableMin[promiseId];
util.assert(promise);
promise.resolve(record);
}
async function sendAsync(
opName,
arg,
zeroCopy,
) {
const promiseId = nextPromiseId(); // AKA cmdId
scratch32[0] = promiseId;
scratch32[1] = arg;
scratch32[2] = 0; // result
const promise = util.createResolvable();
const buf = core.dispatchByName(opName, scratchBytes, zeroCopy);
if (buf != null) {
const record = recordFromBufMinimal(buf);
// Sync result.
promise.resolve(record);
} else {
// Async result.
promiseTableMin[promiseId] = promise;
}
const res = await promise;
return unwrapResponse(res);
}
function sendSync(
opName,
arg,
zeroCopy,
) {
scratch32[0] = 0; // promiseId 0 indicates sync
scratch32[1] = arg;
const res = core.dispatchByName(opName, scratchBytes, zeroCopy);
const resRecord = recordFromBufMinimal(res);
return unwrapResponse(resRecord);
}
window.__bootstrap.dispatchMinimal = {
asyncMsgFromRust,
sendSync,
sendAsync,
};
})(this);