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src: add -r/--require flags for preloading modules
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-r/--require can be used to preload modules on node startup. The option
takes a single module name. The option can be repeated as necessary to
preload multiple modules.

This patch allows 'vendors' (such a cloud host) to inject functionality
that gets executed at application startup without requiring an explicit
require from the user's application. This can be useful to load vendor
specific application monitoring APIs transparently.

PR-URL: #881
Reviewed-By: Trevor Norris <[email protected]>
Reviewed-By: Chris Dickinson <[email protected]>
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@ofrobots @chrisdickinson
ofrobots authored and chrisdickinson committed Mar 13, 2015
1 parent 53e200a commit 7bde3f1
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Showing 7 changed files with 194 additions and 65 deletions.
2 changes: 2 additions & 0 deletions doc/iojs.1
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Expand Up @@ -52,6 +52,8 @@ and servers.
-i, --interactive always enter the REPL even if stdin
does not appear to be a terminal

-r, --require module to preload at startup

--no-deprecation silence deprecation warnings

--trace-deprecation show stack traces on deprecations
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37 changes: 37 additions & 0 deletions src/node.cc
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Expand Up @@ -114,6 +114,8 @@ static bool trace_deprecation = false;
static bool throw_deprecation = false;
static bool abort_on_uncaught_exception = false;
static const char* eval_string = nullptr;
static unsigned int preload_module_count = 0;
static const char** preload_modules = nullptr;
static bool use_debug_agent = false;
static bool debug_wait_connect = false;
static int debug_port = 5858;
Expand Down Expand Up @@ -2765,6 +2767,19 @@ void SetupProcessObject(Environment* env,
READONLY_PROPERTY(process, "_forceRepl", True(env->isolate()));
}

if (preload_module_count) {
CHECK(preload_modules);
Local<Array> array = Array::New(env->isolate());
for (unsigned int i = 0; i < preload_module_count; ++i) {
Local<String> module = String::NewFromUtf8(env->isolate(),
preload_modules[i]);
array->Set(i, module);
}
READONLY_PROPERTY(process,
"_preload_modules",
array);
}

// --no-deprecation
if (no_deprecation) {
READONLY_PROPERTY(process, "noDeprecation", True(env->isolate()));
Expand Down Expand Up @@ -2989,6 +3004,7 @@ static void PrintHelp() {
" -p, --print evaluate script and print result\n"
" -i, --interactive always enter the REPL even if stdin\n"
" does not appear to be a terminal\n"
" -r, --require module to preload (option can be repeated)\n"
" --no-deprecation silence deprecation warnings\n"
" --throw-deprecation throw an exception anytime a deprecated "
"function is used\n"
Expand Down Expand Up @@ -3046,11 +3062,13 @@ static void ParseArgs(int* argc,
const char** new_exec_argv = new const char*[nargs];
const char** new_v8_argv = new const char*[nargs];
const char** new_argv = new const char*[nargs];
const char** local_preload_modules = new const char*[nargs];

for (unsigned int i = 0; i < nargs; ++i) {
new_exec_argv[i] = nullptr;
new_v8_argv[i] = nullptr;
new_argv[i] = nullptr;
local_preload_modules[i] = nullptr;
}

// exec_argv starts with the first option, the other two start with argv[0].
Expand Down Expand Up @@ -3099,6 +3117,15 @@ static void ParseArgs(int* argc,
eval_string += 1;
}
}
} else if (strcmp(arg, "--require") == 0 ||
strcmp(arg, "-r") == 0) {
const char* module = argv[index + 1];
if (module == nullptr) {
fprintf(stderr, "%s: %s requires an argument\n", argv[0], arg);
exit(9);
}
args_consumed += 1;
local_preload_modules[preload_module_count++] = module;
} else if (strcmp(arg, "--interactive") == 0 || strcmp(arg, "-i") == 0) {
force_repl = true;
} else if (strcmp(arg, "--no-deprecation") == 0) {
Expand Down Expand Up @@ -3145,6 +3172,16 @@ static void ParseArgs(int* argc,
memcpy(argv, new_argv, new_argc * sizeof(*argv));
delete[] new_argv;
*argc = static_cast<int>(new_argc);

// Copy the preload_modules from the local array to an appropriately sized
// global array.
if (preload_module_count > 0) {
CHECK(!preload_modules);
preload_modules = new const char*[preload_module_count];
memcpy(preload_modules, local_preload_modules,
preload_module_count * sizeof(*preload_modules));
}
delete[] local_preload_modules;
}


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142 changes: 77 additions & 65 deletions src/node.js
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Expand Up @@ -68,84 +68,96 @@
var d = NativeModule.require('_debug_agent');
d.start();

} else if (process._eval != null) {
// User passed '-e' or '--eval' arguments to Node.
evalScript('[eval]');
} else if (process.argv[1]) {
// make process.argv[1] into a full path
var path = NativeModule.require('path');
process.argv[1] = path.resolve(process.argv[1]);

// If this is a worker in cluster mode, start up the communication
// channel.
if (process.env.NODE_UNIQUE_ID) {
var cluster = NativeModule.require('cluster');
cluster._setupWorker();
} else {
// There is user code to be run

// Make sure it's not accidentally inherited by child processes.
delete process.env.NODE_UNIQUE_ID;
// Load any preload modules
if (process._preload_modules) {
var Module = NativeModule.require('module');
process._preload_modules.forEach(function(module) {
Module._load(module);
});
}

var Module = NativeModule.require('module');
if (process._eval != null) {
// User passed '-e' or '--eval' arguments to Node.
evalScript('[eval]');
} else if (process.argv[1]) {
// make process.argv[1] into a full path
var path = NativeModule.require('path');
process.argv[1] = path.resolve(process.argv[1]);

// If this is a worker in cluster mode, start up the communication
// channel.
if (process.env.NODE_UNIQUE_ID) {
var cluster = NativeModule.require('cluster');
cluster._setupWorker();

// Make sure it's not accidentally inherited by child processes.
delete process.env.NODE_UNIQUE_ID;
}

if (global.v8debug &&
process.execArgv.some(function(arg) {
return arg.match(/^--debug-brk(=[0-9]*)?$/);
})) {
var Module = NativeModule.require('module');

// XXX Fix this terrible hack!
//
// Give the client program a few ticks to connect.
// Otherwise, there's a race condition where `node debug foo.js`
// will not be able to connect in time to catch the first
// breakpoint message on line 1.
//
// A better fix would be to somehow get a message from the
// global.v8debug object about a connection, and runMain when
// that occurs. --isaacs
if (global.v8debug &&
process.execArgv.some(function(arg) {
return arg.match(/^--debug-brk(=[0-9]*)?$/);
})) {

var debugTimeout = +process.env.NODE_DEBUG_TIMEOUT || 50;
setTimeout(Module.runMain, debugTimeout);
// XXX Fix this terrible hack!
//
// Give the client program a few ticks to connect.
// Otherwise, there's a race condition where `node debug foo.js`
// will not be able to connect in time to catch the first
// breakpoint message on line 1.
//
// A better fix would be to somehow get a message from the
// global.v8debug object about a connection, and runMain when
// that occurs. --isaacs

} else {
// Main entry point into most programs:
Module.runMain();
}
var debugTimeout = +process.env.NODE_DEBUG_TIMEOUT || 50;
setTimeout(Module.runMain, debugTimeout);

} else {
var Module = NativeModule.require('module');

// If -i or --interactive were passed, or stdin is a TTY.
if (process._forceRepl || NativeModule.require('tty').isatty(0)) {
// REPL
var opts = {
useGlobal: true,
ignoreUndefined: false
};
if (parseInt(process.env['NODE_NO_READLINE'], 10)) {
opts.terminal = false;
}
if (parseInt(process.env['NODE_DISABLE_COLORS'], 10)) {
opts.useColors = false;
} else {
// Main entry point into most programs:
Module.runMain();
}
var repl = Module.requireRepl().start(opts);
repl.on('exit', function() {
process.exit();
});

} else {
// Read all of stdin - execute it.
process.stdin.setEncoding('utf8');
var Module = NativeModule.require('module');

// If -i or --interactive were passed, or stdin is a TTY.
if (process._forceRepl || NativeModule.require('tty').isatty(0)) {
// REPL
var opts = {
useGlobal: true,
ignoreUndefined: false
};
if (parseInt(process.env['NODE_NO_READLINE'], 10)) {
opts.terminal = false;
}
if (parseInt(process.env['NODE_DISABLE_COLORS'], 10)) {
opts.useColors = false;
}
var repl = Module.requireRepl().start(opts);
repl.on('exit', function() {
process.exit();
});

var code = '';
process.stdin.on('data', function(d) {
code += d;
});
} else {
// Read all of stdin - execute it.
process.stdin.setEncoding('utf8');

process.stdin.on('end', function() {
process._eval = code;
evalScript('[stdin]');
});
var code = '';
process.stdin.on('data', function(d) {
code += d;
});

process.stdin.on('end', function() {
process._eval = code;
evalScript('[stdin]');
});
}
}
}
}
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1 change: 1 addition & 0 deletions test/fixtures/printA.js
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@@ -0,0 +1 @@
console.log('A')
1 change: 1 addition & 0 deletions test/fixtures/printB.js
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@@ -0,0 +1 @@
console.log('B')
1 change: 1 addition & 0 deletions test/fixtures/printC.js
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@@ -0,0 +1 @@
console.log('C')
75 changes: 75 additions & 0 deletions test/parallel/test-preload.js
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@@ -0,0 +1,75 @@
var common = require('../common'),
assert = require('assert'),
path = require('path'),
child_process = require('child_process');

var nodeBinary = process.argv[0];

var preloadOption = function(preloads) {
var option = '';
preloads.forEach(function(preload, index) {
// TODO: randomly pick -r or --require
option += '-r ' + preload + ' ';
});
return option;
}

var fixture = function(name) {
return path.join(__dirname, '../fixtures/' + name);
}

var fixtureA = fixture('printA.js');
var fixtureB = fixture('printB.js');
var fixtureC = fixture('printC.js')
var fixtureThrows = fixture('throws_error4.js');

// test preloading a single module works
child_process.exec(nodeBinary + ' '
+ preloadOption([fixtureA]) + ' '
+ fixtureB,
function(err, stdout, stderr) {
if (err) throw err;
assert.equal(stdout, 'A\nB\n');
});

// test preloading multiple modules works
child_process.exec(nodeBinary + ' '
+ preloadOption([fixtureA, fixtureB]) + ' '
+ fixtureC,
function(err, stdout, stderr) {
if (err) throw err;
assert.equal(stdout, 'A\nB\nC\n');
});

// test that preloading a throwing module aborts
child_process.exec(nodeBinary + ' '
+ preloadOption([fixtureA, fixtureThrows]) + ' '
+ fixtureB,
function(err, stdout, stderr) {
if (err) {
assert.equal(stdout, 'A\n');
} else {
throw new Error('Preload should have failed');
}
});

// test that preload can be used with --eval
child_process.exec(nodeBinary + ' '
+ preloadOption([fixtureA])
+ '-e \'console.log("hello");\'',
function(err, stdout, stderr) {
if (err) throw err;
assert.equal(stdout, 'A\nhello\n');
});

// test that preload placement at other points in the cmdline
// also test that duplicated preload only gets loaded once
child_process.exec(nodeBinary + ' '
+ preloadOption([fixtureA])
+ '-e \'console.log("hello");\' '
+ preloadOption([fixtureA, fixtureB]),
function(err, stdout, stderr) {
if (err) throw err;
assert.equal(stdout, 'A\nB\nhello\n');
});

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