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lib: print to stdout/stderr directly instead of using console
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This patch adds an internal function that prints to stdout or
stderr by directly writing to the known file descriptor, and
uses it internally in common cases to avoid the overhead
of the console implementation.

PR-URL: #27320
Reviewed-By: James M Snell <jasnell@gmail.com>
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joyeecheung committed Apr 28, 2019
1 parent 31b3dd2 commit 2b24ffa
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Showing 6 changed files with 103 additions and 35 deletions.
20 changes: 2 additions & 18 deletions lib/fs.js
Original file line number Diff line number Diff line change
Expand Up @@ -74,7 +74,8 @@ const {
validateOffsetLengthRead,
validateOffsetLengthWrite,
validatePath,
warnOnNonPortableTemplate
warnOnNonPortableTemplate,
handleErrorFromBinding
} = require('internal/fs/utils');
const {
CHAR_FORWARD_SLASH,
Expand Down Expand Up @@ -117,23 +118,6 @@ function showTruncateDeprecation() {
}
}

function handleErrorFromBinding(ctx) {
if (ctx.errno !== undefined) { // libuv error numbers
const err = uvException(ctx);
// eslint-disable-next-line no-restricted-syntax
Error.captureStackTrace(err, handleErrorFromBinding);
throw err;
}
if (ctx.error !== undefined) { // Errors created in C++ land.
// TODO(joyeecheung): currently, ctx.error are encoding errors
// usually caused by memory problems. We need to figure out proper error
// code(s) for this.
// eslint-disable-next-line no-restricted-syntax
Error.captureStackTrace(ctx.error, handleErrorFromBinding);
throw ctx.error;
}
}

function maybeCallback(cb) {
if (typeof cb === 'function')
return cb;
Expand Down
22 changes: 21 additions & 1 deletion lib/internal/fs/utils.js
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,8 @@ const {
ERR_INVALID_OPT_VALUE_ENCODING,
ERR_OUT_OF_RANGE
},
hideStackFrames
hideStackFrames,
uvException
} = require('internal/errors');
const {
isUint8Array,
Expand Down Expand Up @@ -444,7 +445,26 @@ function warnOnNonPortableTemplate(template) {
}
}

// This handles errors following the convention of the fs binding.
function handleErrorFromBinding(ctx) {
if (ctx.errno !== undefined) { // libuv error numbers
const err = uvException(ctx);
// eslint-disable-next-line no-restricted-syntax
Error.captureStackTrace(err, handleErrorFromBinding);
throw err;
}
if (ctx.error !== undefined) { // Errors created in C++ land.
// TODO(joyeecheung): currently, ctx.error are encoding errors
// usually caused by memory problems. We need to figure out proper error
// code(s) for this.
// eslint-disable-next-line no-restricted-syntax
Error.captureStackTrace(ctx.error, handleErrorFromBinding);
throw ctx.error;
}
}

module.exports = {
handleErrorFromBinding,
assertEncoding,
copyObject,
Dirent,
Expand Down
10 changes: 4 additions & 6 deletions lib/internal/main/repl.js
Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ const {
evalScript
} = require('internal/process/execution');

const console = require('internal/console/global');
const { print, kStderr, kStdout } = require('internal/util/print');

const { getOptionValue } = require('internal/options');

Expand All @@ -21,14 +21,12 @@ markBootstrapComplete();

// --input-type flag not supported in REPL
if (getOptionValue('--input-type')) {
// If we can't write to stderr, we'd like to make this a noop,
// so use console.error.
console.error('Cannot specify --input-type for REPL');
print(kStderr, 'Cannot specify --input-type for REPL');
process.exit(1);
}

console.log(`Welcome to Node.js ${process.version}.\n` +
'Type ".help" for more information.');
print(kStdout, `Welcome to Node.js ${process.version}.\n` +
'Type ".help" for more information.');

const cliRepl = require('internal/repl');
cliRepl.createInternalRepl(process.env, (err, repl) => {
Expand Down
18 changes: 8 additions & 10 deletions lib/internal/process/execution.js
Original file line number Diff line number Diff line change
Expand Up @@ -35,26 +35,24 @@ function tryGetCwd() {
}
}

function evalModule(source, print) {
const { log, error } = require('internal/console/global');
function evalModule(source, printResult) {
const { decorateErrorStack } = require('internal/util');
const asyncESM = require('internal/process/esm_loader');
const { kStdout, kStderr, print } = require('internal/util/print');
asyncESM.loaderPromise.then(async (loader) => {
const { result } = await loader.eval(source);
if (print) {
log(result);
}
if (printResult) { print(kStdout, result); }
})
.catch((e) => {
decorateErrorStack(e);
error(e);
print(kStderr, e);
process.exit(1);
});
// Handle any nextTicks added in the first tick of the program.
process._tickCallback();
}

function evalScript(name, body, breakFirstLine, print) {
function evalScript(name, body, breakFirstLine, printResult) {
const CJSModule = require('internal/modules/cjs/loader');
const { kVmBreakFirstLineSymbol } = require('internal/util');

Expand All @@ -79,9 +77,9 @@ function evalScript(name, body, breakFirstLine, print) {
[kVmBreakFirstLineSymbol]: ${!!breakFirstLine}
});\n`;
const result = module._compile(script, `${name}-wrapper`);
if (print) {
const { log } = require('internal/console/global');
log(result);
if (printResult) {
const { kStdout, print } = require('internal/util/print');
print(kStdout, result);
}
// Handle any nextTicks added in the first tick of the program.
process._tickCallback();
Expand Down
67 changes: 67 additions & 0 deletions lib/internal/util/print.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,67 @@
'use strict';

// This implements a light-weight printer that writes to stdout/stderr
// directly to avoid the overhead in the console abstraction.

const { formatWithOptions } = require('internal/util/inspect');
const { writeString } = internalBinding('fs');
const { handleErrorFromBinding } = require('internal/fs/utils');
const { guessHandleType } = internalBinding('util');
const { log } = require('internal/console/global');

const kStdout = 1;
const kStderr = 2;
const handleType = [undefined, undefined, undefined];
function getFdType(fd) {
if (handleType[fd] === undefined) {
handleType[fd] = guessHandleType(fd);
}
return handleType[fd];
}

function formatAndWrite(fd, obj, ignoreErrors, colors = false) {
const str = `${formatWithOptions({ colors }, obj)}\n`;
const ctx = {};
writeString(fd, str, null, undefined, undefined, ctx);
if (!ignoreErrors) {
handleErrorFromBinding(ctx);
}
}

let colors;
function getColors() {
if (colors === undefined) {
colors = require('internal/tty').getColorDepth() > 2;
}
return colors;
}

// TODO(joyeecheung): replace more internal process._rawDebug()
// and console.log() usage with this if possible.
function print(fd, obj, ignoreErrors = true) {
switch (getFdType(fd)) {
case 'TTY':
formatAndWrite(fd, obj, ignoreErrors, getColors());
break;
case 'FILE':
formatAndWrite(fd, obj, ignoreErrors);
break;
case 'PIPE':
case 'TCP':
// Fallback to console.log to handle IPC.
if (process.channel && process.channel.fd === fd) {
log(obj);
} else {
formatAndWrite(fd, obj, ignoreErrors);
}
break;
default:
log(obj);
}
}

module.exports = {
print,
kStderr,
kStdout
};
1 change: 1 addition & 0 deletions node.gyp
Original file line number Diff line number Diff line change
Expand Up @@ -184,6 +184,7 @@
'lib/internal/url.js',
'lib/internal/util.js',
'lib/internal/util/comparisons.js',
'lib/internal/util/print.js',
'lib/internal/util/debuglog.js',
'lib/internal/util/inspect.js',
'lib/internal/util/inspector.js',
Expand Down

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