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Code Issues Packages 1 Wiki Activity

Use multimap with Persistent module handle to avoid IdentityHash collision (#1466)

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Kevin (Kun) "Kassimo" Qian 2019-01-07 18:18:32 -08:00 committed by Ryan Dahl
parent 404e6f8634
commit 2558d6e184
2 changed files with 28 additions and 10 deletions
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33
libdeno/binding.cc
View file

@ -378,21 +378,26 @@ void DenoIsolate::ClearModules() {
it->second.Reset();
}
module_map_.clear();
module_filename_map_.clear();
for (auto it = module_info_map_.begin(); it != module_info_map_.end(); it++) {
it->second.second.Reset();
}
module_info_map_.clear();
}
void DenoIsolate::RegisterModule(const char* filename,
v8::Local<v8::Module> module) {
int id = module->GetIdentityHash();
// v8.h says that identity hash is not necessarily unique. It seems it's quite
// unique enough for the purposes of O(1000) modules, so we use it as a
// hashmap key here. The following check is to detect collisions.
CHECK_EQ(0, module_filename_map_.count(id));
module_filename_map_[id] = filename;
module_map_.emplace(std::piecewise_construct, std::make_tuple(filename),
std::make_tuple(isolate_, module));
// Identity hash is not necessarily unique
// Therefore, we store a persistent handle along with filenames
// such that we can compare the identites and select the correct module
module_info_map_.emplace(
std::piecewise_construct, std::make_tuple(id),
std::make_tuple(std::piecewise_construct, std::make_tuple(filename),
std::make_tuple(isolate_, module)));
}
v8::MaybeLocal<v8::Module> CompileModule(v8::Local<v8::Context> context,
@ -468,7 +473,19 @@ v8::MaybeLocal<v8::Module> ResolveCallback(v8::Local<v8::Context> context,
}
int ref_id = referrer->GetIdentityHash();
std::string referrer_filename = d->module_filename_map_[ref_id];
auto range = d->module_info_map_.equal_range(ref_id);
std::string referrer_filename;
for (auto it = range.first; it != range.second; ++it) {
// it->second: <string, v8::Persistent<v8::Module>>
// operator== compares value identities stored in the handles
// https://denolib.github.io/v8-docs/include_2v8_8h_source.html#l00487
// Due to possibilities of identity hash collision, this is necessary
if (it->second.second == referrer) {
referrer_filename = it->second.first;
break;
}
}
CHECK(referrer_filename.size() != 0);
v8::String::Utf8Value specifier_(isolate, specifier);
const char* specifier_c = ToCString(specifier_);

5
libdeno/internal.h
View file

@ -58,8 +58,9 @@ class DenoIsolate {
int32_t next_req_id_;
void* user_data_;
// identity hash -> filename
std::map<int, std::string> module_filename_map_;
// identity hash -> filename, module (avoid hash collision)
std::multimap<int, std::pair<std::string, v8::Persistent<v8::Module>>>
module_info_map_;
// filename -> Module
std::map<std::string, v8::Persistent<v8::Module>> module_map_;
// Set by deno_resolve_ok