8000 n-api: re-use napi_env between modules · nodejs/node@86b101c · GitHub
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Gabriel SchulhofMylesBorins
Gabriel Schulhof
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MylesBorins
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n-api: re-use napi_env between modules
Store the `napi_env` on the global object at a private key. This gives us one `napi_env` per context. Refs: #14367 Backport-PR-URL: #19447 PR-URL: #14217 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Timothy Gu <timothygu99@gmail.com>
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‎src/node_api.cc‎

Lines changed: 42 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -712,6 +712,45 @@ bool FindWrapper(v8::Local<v8::Object> obj,
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return true;
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}
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static void DeleteEnv(napi_env env, void* data, void* hint) {
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delete env;
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}
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napi_env GetEnv(v8::Local<v8::Context> context) {
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napi_env result;
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auto isolate = context->GetIsolate();
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auto global = context->Global();
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// In the case of the string for which we grab the private and the value of
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// the private on the global object we can call .ToLocalChecked() directly
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// because we need to stop hard if either of them is empty.
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//
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// Re https://github.com/nodejs/node/pull/14217#discussion_r128775149
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auto key = v8::Private::ForApi(isolate,
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v8::String::NewFromOneByte(isolate,
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reinterpret_cast<const uint8_t*>("N-API Environment"),
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v8::NewStringType::kInternalized).ToLocalChecked());
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auto value = global->GetPrivate(context, key).ToLocalChecked();
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if (value->IsExternal()) {
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result = static_cast<napi_env>(value.As<v8::External>()->Value());
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} else {
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result = new napi_env__(isolate);
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auto external = v8::External::New(isolate, result);
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// We must also stop hard if the result of assigning the env to the global
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// is either nothing or false.
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CHECK(global->SetPrivate(context, key, external).FromJust());
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// Create a self-destructing reference to external that will get rid of the
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// napi_env when external goes out of scope.
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Reference::New(result, external, 0, true, DeleteEnv, nullptr, nullptr);
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}
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return result;
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}
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} // end of namespace v8impl
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// Intercepts the Node-V8 module registration callback. Converts parameters
@@ -723,9 +762,9 @@ void napi_module_register_cb(v8::Local<v8::Object> exports,
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void* priv) {
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napi_module* mod = static_cast<napi_module*>(priv);
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// Create a new napi_env for this module. Once module unloading is supported
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// we shall have to call delete on this object from there.
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napi_env env = new napi_env__(context->GetIsolate());
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// Create a new napi_env for this module or reference one if a pre-existing
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// one is found.
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napi_env env = v8impl::GetEnv(context);
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mod->nm_register_func(
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env,

‎test/addons-napi/test_env_sharing/binding.gyp‎

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,12 @@
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{
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"targets": [
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{
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"target_name": "store_env",
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"sources": [ "store_env.c" ]
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},
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{
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"target_name": "compare_env",
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"sources": [ "compare_env.c" ]
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}
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]
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}

‎test/addons-napi/test_env_sharing/compare_env.c‎

Lines changed: 22 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,22 @@
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#include <node_api.h>
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#include "../common.h"
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napi_value compare(napi_env env, napi_callback_info info) {
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napi_value external;
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size_t argc = 1;
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void* data;
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napi_value return_value;
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NAPI_CALL(env, napi_get_cb_info(env, info, &argc, &external, NULL, NULL));
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NAPI_CALL(env, napi_get_value_external(env, external, &data));
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NAPI_CALL(env, napi_get_boolean(env, ((napi_env)data) == env, &return_value));
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return return_value;
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}
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void Init(napi_env env, napi_value exports, napi_value module, void* context) {
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napi_property_descriptor prop = DECLARE_NAPI_PROPERTY("exports", compare);
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NAPI_CALL_RETURN_VOID(env, napi_define_properties(env, module, 1, &prop));
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}
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NAPI_MODULE(compare_env, Init)

‎test/addons-napi/test_env_sharing/store_env.c‎

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,12 @@
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#include <node_api.h>
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#include "../common.h"
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void Init(napi_env env, napi_value exports, napi_value module, void* context) {
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napi_value external;
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NAPI_CALL_RETURN_VOID(env,
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napi_create_external(env, env, NULL, NULL, &external));
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NAPI_CALL_RETURN_VOID(env,
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napi_set_named_property(env, module, "exports", external));
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}
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NAPI_MODULE(store_env, Init)

‎test/addons-napi/test_env_sharing/test.js‎

Lines changed: 10 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,10 @@
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'use strict';
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const common = require('../../common');
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const storeEnv = require(`./build/${common.buildType}/store_env`);
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const compareEnv = require(`./build/${common.buildType}/compare_env`);
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const assert = require('assert');
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assert.strictEqual(compareEnv(storeEnv), true,
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'N-API environment pointers in two different modules have ' +
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'the same value');

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