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arangodb/arangod/V8Server/V8DealerFeature.cpp

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////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2016 ArangoDB GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
/// http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Dr. Frank Celler
////////////////////////////////////////////////////////////////////////////////
#include "V8DealerFeature.h"
#include <thread>
#include "3rdParty/valgrind/valgrind.h"
#include "Actions/actions.h"
#include "ApplicationFeatures/MaxMapCountFeature.h"
#include "ApplicationFeatures/V8PlatformFeature.h"
#include "Basics/ArangoGlobalContext.h"
#include "Basics/ConditionLocker.h"
#include "Basics/FileUtils.h"
#include "Basics/StringUtils.h"
#include "Basics/TimedAction.h"
#include "Basics/WorkMonitor.h"
#include "Cluster/ServerState.h"
#include "Logger/Logger.h"
#include "ProgramOptions/ProgramOptions.h"
#include "ProgramOptions/Section.h"
#include "Random/RandomGenerator.h"
#include "RestServer/DatabaseFeature.h"
#include "Scheduler/JobGuard.h"
#include "Scheduler/SchedulerFeature.h"
#include "Transaction/V8Context.h"
#include "V8/v8-buffer.h"
#include "V8/v8-conv.h"
#include "V8/v8-globals.h"
#include "V8/v8-shell.h"
#include "V8/v8-utils.h"
#include "V8Server/V8Context.h"
#include "V8Server/v8-actions.h"
#include "V8Server/v8-user-functions.h"
#include "V8Server/v8-user-structures.h"
#include "VocBase/vocbase.h"
using namespace arangodb;
using namespace arangodb::application_features;
using namespace arangodb::basics;
using namespace arangodb::options;
V8DealerFeature* V8DealerFeature::DEALER = nullptr;
static thread_local bool alreadyLockedInThread = false;
namespace {
class V8GcThread : public Thread {
public:
explicit V8GcThread(V8DealerFeature* dealer)
: Thread("V8GarbageCollector"),
_dealer(dealer),
_lastGcStamp(static_cast<uint64_t>(TRI_microtime())) {}
~V8GcThread() { shutdown(); }
public:
void run() override { _dealer->collectGarbage(); }
double getLastGcStamp() {
return static_cast<double>(_lastGcStamp.load(std::memory_order_acquire));
}
void updateGcStamp(double value) {
_lastGcStamp.store(static_cast<uint64_t>(value), std::memory_order_release);
}
private:
V8DealerFeature* _dealer;
std::atomic<uint64_t> _lastGcStamp;
};
}
V8DealerFeature::V8DealerFeature(
application_features::ApplicationServer* server)
: application_features::ApplicationFeature(server, "V8Dealer"),
_gcFrequency(30.0),
_gcInterval(1000),
_maxContextAge(60.0),
_nrMaxContexts(0),
_nrMinContexts(0),
_nrInflightContexts(0),
_maxContextInvocations(0),
_allowAdminExecute(false),
_nextId(0),
_stopping(false),
_gcFinished(false),
_dynamicContextCreationBlockers(0) {
setOptional(false);
requiresElevatedPrivileges(false);
startsAfter("Action");
startsAfter("Authentication");
startsAfter("Database");
startsAfter("Random");
startsAfter("Scheduler");
startsAfter("V8Platform");
startsAfter("WorkMonitor");
startsAfter("Temp");
}
void V8DealerFeature::collectOptions(std::shared_ptr<ProgramOptions> options) {
options->addSection("javascript", "Configure the Javascript engine");
options->addHiddenOption(
"--javascript.gc-frequency",
"JavaScript time-based garbage collection frequency (each x seconds)",
new DoubleParameter(&_gcFrequency));
options->addHiddenOption(
"--javascript.gc-interval",
"JavaScript request-based garbage collection interval (each x requests)",
new UInt64Parameter(&_gcInterval));
options->addOption("--javascript.app-path", "directory for Foxx applications",
new StringParameter(&_appPath));
options->addOption(
"--javascript.startup-directory",
"path to the directory containing JavaScript startup scripts",
new StringParameter(&_startupDirectory));
options->addHiddenOption(
"--javascript.module-directory",
"additional paths containing JavaScript modules",
new VectorParameter<StringParameter>(&_moduleDirectory));
options->addOption(
"--javascript.v8-contexts",
"maximum number of V8 contexts that are created for executing JavaScript actions",
new UInt64Parameter(&_nrMaxContexts));
options->addOption(
"--javascript.v8-contexts-minimum",
"minimum number of V8 contexts that keep available for executing JavaScript actions",
new UInt64Parameter(&_nrMinContexts));
options->addHiddenOption(
"--javascript.v8-contexts-max-invocations",
"maximum number of invocations for each V8 context before it is disposed",
new UInt64Parameter(&_maxContextInvocations));
options->addHiddenOption(
"--javascript.v8-contexts-max-age",
"maximum age for each V8 context (in seconds) before it is disposed",
new DoubleParameter(&_maxContextAge));
options->addHiddenOption(
"--javascript.allow-admin-execute",
"for testing purposes allow '_admin/execute', NEVER enable on production",
new BooleanParameter(&_allowAdminExecute));
}
void V8DealerFeature::validateOptions(std::shared_ptr<ProgramOptions> options) {
// check the startup path
if (_startupDirectory.empty()) {
LOG_TOPIC(FATAL, arangodb::Logger::V8)
<< "no 'javascript.startup-directory' has been supplied, giving up";
FATAL_ERROR_EXIT();
}
// remove trailing / from path and set path
auto ctx = ArangoGlobalContext::CONTEXT;
if (ctx == nullptr) {
LOG_TOPIC(FATAL, arangodb::Logger::V8) << "failed to get global context";
FATAL_ERROR_EXIT();
}
ctx->normalizePath(_startupDirectory, "javascript.startup-directory", true);
ctx->normalizePath(_moduleDirectory, "javascript.module-directory", false);
_startupLoader.setDirectory(_startupDirectory);
ServerState::instance()->setJavaScriptPath(_startupDirectory);
// check whether app-path was specified
if (_appPath.empty()) {
LOG_TOPIC(FATAL, arangodb::Logger::V8) << "no value has been specified for --javascript.app-path";
FATAL_ERROR_EXIT();
}
// Tests if this path is either a directory (ok) or does not exist (we create it in ::start)
// If it is something else this will throw an error.
ctx->normalizePath(_appPath, "javascript.app-path", false);
// use a minimum of 1 second for GC
if (_gcFrequency < 1) {
_gcFrequency = 1;
}
}
void V8DealerFeature::start() {
// dump paths
{
std::vector<std::string> paths;
paths.push_back(std::string("startup '" + _startupDirectory + "'"));
if (!_moduleDirectory.empty()) {
paths.push_back(std::string(
"module '" + StringUtils::join(_moduleDirectory, ";") + "'"));
}
if (!_appPath.empty()) {
paths.push_back(std::string("application '" + _appPath + "'"));
// create app directory if it does not exist
if (!basics::FileUtils::isDirectory(_appPath)) {
std::string systemErrorStr;
long errorNo;
int res = TRI_CreateRecursiveDirectory(_appPath.c_str(), errorNo,
systemErrorStr);
if (res == TRI_ERROR_NO_ERROR) {
LOG_TOPIC(INFO, arangodb::Logger::FIXME) << "created javascript.app-path directory '" << _appPath << "'";
} else {
LOG_TOPIC(FATAL, arangodb::Logger::FIXME) << "unable to create javascript.app-path directory '" << _appPath << "': " << systemErrorStr;
FATAL_ERROR_EXIT();
}
}
}
LOG_TOPIC(INFO, arangodb::Logger::V8) << "JavaScript using " << StringUtils::join(paths, ", ");
}
// set singleton
DEALER = this;
if (_nrMinContexts < 1) {
_nrMinContexts = 1;
}
// try to guess a suitable number of contexts
if (0 == _nrMaxContexts) {
SchedulerFeature* scheduler =
ApplicationServer::getFeature<SchedulerFeature>("Scheduler");
// automatic maximum number of contexts should not be below 16
// this is because the number of cores may be too few for the cluster
// startup to properly run through with all its parallel requests
// and the potential need for multiple V8 contexts
_nrMaxContexts = (std::max)(uint64_t(scheduler->concurrency()), uint64_t(16));
}
if (_nrMinContexts > _nrMaxContexts) {
// max contexts must not be lower than min contexts
_nrMaxContexts = _nrMinContexts;
}
LOG_TOPIC(DEBUG, Logger::V8) << "number of V8 contexts: min: " << _nrMinContexts << ", max: " << _nrMaxContexts;
defineDouble("V8_CONTEXTS", static_cast<double>(_nrMaxContexts));
defineBoolean("ALLOW_ADMIN_EXECUTE", _allowAdminExecute);
// setup instances
{
CONDITION_LOCKER(guard, _contextCondition);
_contexts.reserve(static_cast<size_t>(_nrMaxContexts));
_busyContexts.reserve(static_cast<size_t>(_nrMaxContexts));
_idleContexts.reserve(static_cast<size_t>(_nrMaxContexts));
_dirtyContexts.reserve(static_cast<size_t>(_nrMaxContexts));
for (size_t i = 0; i < _nrMinContexts; ++i) {
V8Context* context = buildContext(nextId());
try {
_contexts.push_back(context);
} catch (...) {
delete context;
throw;
}
}
TRI_ASSERT(_contexts.size() > 0);
TRI_ASSERT(_contexts.size() <= _nrMaxContexts);
for (auto& context : _contexts) {
// apply context update is only run on contexts that no other
// threads can see (yet)
applyContextUpdate(context);
_idleContexts.push_back(context);
}
}
DatabaseFeature* database =
ApplicationServer::getFeature<DatabaseFeature>("Database");
loadJavaScriptFileInAllContexts(database->systemDatabase(), "server/initialize.js", nullptr);
startGarbageCollection();
}
V8Context* V8DealerFeature::addContext() {
V8Context* context = buildContext(nextId());
try {
// apply context update is only run on contexts that no other
// threads can see (yet)
applyContextUpdate(context);
DatabaseFeature* database =
ApplicationServer::getFeature<DatabaseFeature>("Database");
// no other thread can use the context when we are here, as the
// context has not been added to the global list of contexts yet
loadJavaScriptFileInContext(database->systemDatabase(), "server/initialize.js", context, nullptr);
return context;
} catch (...) {
delete context;
throw;
}
}
void V8DealerFeature::unprepare() {
shutdownContexts();
// delete GC thread after all action threads have been stopped
_gcThread.reset();
DEALER = nullptr;
}
bool V8DealerFeature::addGlobalContextMethod(std::string const& method) {
auto cb = [this, &method]() -> bool {
bool result = true;
for (auto& context : _contexts) {
try {
if (!context->addGlobalContextMethod(method)) {
result = false;
}
} catch (...) {
result = false;
}
}
return result;
};
if (alreadyLockedInThread) {
// the condition lock has already been acquired in this thread
// we cannot detect this easily here without a thread-local variable
// as we may be called from a JavaScript callback here
return cb();
} else {
// the condition lock has not been acquired in this thread, so
// we are responsible for locking properly!
CONDITION_LOCKER(guard, _contextCondition);
return cb();
}
}
void V8DealerFeature::collectGarbage() {
V8GcThread* gc = static_cast<V8GcThread*>(_gcThread.get());
TRI_ASSERT(gc != nullptr);
// this flag will be set to true if we timed out waiting for a GC signal
// if set to true, the next cycle will use a reduced wait time so the GC
// can be performed more early for all dirty contexts. The flag is set
// to false again once all contexts have been cleaned up and there is nothing
// more to do
bool useReducedWait = false;
bool preferFree = false;
// the time we'll wait for a signal
uint64_t const regularWaitTime =
static_cast<uint64_t>(_gcFrequency * 1000.0 * 1000.0);
// the time we'll wait for a signal when the previous wait timed out
uint64_t const reducedWaitTime =
static_cast<uint64_t>(_gcFrequency * 1000.0 * 200.0);
while (!_stopping) {
try {
V8Context* context = nullptr;
bool wasDirty = false;
{
bool gotSignal = false;
preferFree = !preferFree;
CONDITION_LOCKER(guard, _contextCondition);
if (_dirtyContexts.empty()) {
uint64_t waitTime = useReducedWait ? reducedWaitTime : regularWaitTime;
// we'll wait for a signal or a timeout
gotSignal = guard.wait(waitTime);
}
if (preferFree && !_idleContexts.empty()) {
context = pickFreeContextForGc();
}
if (context == nullptr && !_dirtyContexts.empty()) {
context = _dirtyContexts.back();
_dirtyContexts.pop_back();
if (context->invocationsSinceLastGc() < 50 && !context->_hasActiveExternals) {
// don't collect this one yet. it doesn't have externals, so there
// is no urge for garbage collection
_idleContexts.emplace_back(context);
context = nullptr;
} else {
wasDirty = true;
}
}
if (context == nullptr && !preferFree && !gotSignal &&
!_idleContexts.empty()) {
// we timed out waiting for a signal, so we have idle time that we can
// spend on running the GC pro-actively
// We'll pick one of the free contexts and clean it up
context = pickFreeContextForGc();
}
// there is no context to clean up, probably they all have been cleaned up
// already. increase the wait time so we don't cycle too much in the GC
// loop
// and waste CPU unnecessary
useReducedWait = (context != nullptr);
}
// update last gc time
double lastGc = TRI_microtime();
gc->updateGcStamp(lastGc);
if (context != nullptr) {
arangodb::CustomWorkStack custom("V8 GC", (uint64_t)context->id());
LOG_TOPIC(TRACE, arangodb::Logger::V8) << "collecting V8 garbage in context #" << context->id()
<< ", invocations total: " << context->invocations()
<< ", invocations since last gc: " << context->invocationsSinceLastGc()
<< ", hasActive: " << context->_hasActiveExternals
<< ", wasDirty: " << wasDirty;
bool hasActiveExternals = false;
auto isolate = context->_isolate;
{
// this guard will lock and enter the isolate
// and automatically exit and unlock it when it runs out of scope
V8ContextEntryGuard contextGuard(context);
v8::HandleScope scope(isolate);
auto localContext =
v8::Local<v8::Context>::New(isolate, context->_context);
localContext->Enter();
{
v8::Context::Scope contextScope(localContext);
context->assertLocked();
TRI_GET_GLOBALS();
TRI_RunGarbageCollectionV8(isolate, 1.0);
hasActiveExternals = v8g->hasActiveExternals();
}
localContext->Exit();
}
// update garbage collection statistics
context->_hasActiveExternals = hasActiveExternals;
context->setCleaned(lastGc);
{
CONDITION_LOCKER(guard, _contextCondition);
if (_contexts.size() > _nrMinContexts &&
!context->isDefault() &&
context->shouldBeRemoved(_maxContextAge, _maxContextInvocations) &&
_dynamicContextCreationBlockers == 0) {
// remove the extra context as it is not needed anymore
_contexts.erase(std::remove_if(_contexts.begin(), _contexts.end(), [&context](V8Context* c) {
return (c->id() == context->id());
}));
LOG_TOPIC(DEBUG, Logger::V8) << "removed superfluous V8 context #" << context->id() << ", number of contexts is now: " << _contexts.size();
guard.unlock();
shutdownContext(context);
} else {
// put it back into the free list
if (wasDirty) {
_idleContexts.emplace_back(context);
} else {
_idleContexts.insert(_idleContexts.begin(), context);
}
guard.broadcast();
}
}
} else {
useReducedWait = true; // sanity
}
} catch (...) {
// simply ignore errors here
useReducedWait = false;
}
}
_gcFinished = true;
}
void V8DealerFeature::unblockDynamicContextCreation() {
CONDITION_LOCKER(guard, _contextCondition);
TRI_ASSERT(_dynamicContextCreationBlockers > 0);
--_dynamicContextCreationBlockers;
}
void V8DealerFeature::loadJavaScriptFileInAllContexts(TRI_vocbase_t* vocbase,
std::string const& file, VPackBuilder* builder) {
alreadyLockedInThread = true;
TRI_DEFER(alreadyLockedInThread = false);
if (builder != nullptr) {
builder->openArray();
}
std::vector<V8Context*> contexts;
{
CONDITION_LOCKER(guard, _contextCondition);
while (_nrInflightContexts > 0) {
// wait until all pending context creation requests have been satisified
guard.wait(10000);
}
// copy the list of contexts into a local variable
contexts = _contexts;
// block the addition or removal of contexts
++_dynamicContextCreationBlockers;
}
TRI_DEFER(unblockDynamicContextCreation());
LOG_TOPIC(TRACE, Logger::V8) << "loading JavaScript file '" << file << "' in all (" << contexts.size() << ") V8 context";
// now safely scan the local copy of the contexts
for (auto& context : contexts) {
CONDITION_LOCKER(guard, _contextCondition);
while (_busyContexts.find(context) != _busyContexts.end()) {
// we must not enter the context if another thread is also using it...
guard.wait(10000);
}
auto it = std::find(_dirtyContexts.begin(), _dirtyContexts.end(), context);
if (it != _dirtyContexts.end()) {
// context is in _dirtyContexts
// remove it from there
_dirtyContexts.erase(it);
guard.unlock();
try {
loadJavaScriptFileInContext(vocbase, file, context, builder);
} catch (...) {
guard.lock();
_dirtyContexts.push_back(context);
throw;
}
// and re-insert it after we are done
guard.lock();
_dirtyContexts.push_back(context);
} else {
// if the context is neither busy nor dirty, it must be idle
auto it = std::find(_idleContexts.begin(), _idleContexts.end(), context);
if (it != _idleContexts.end()) {
// remove it from there
_idleContexts.erase(it);
guard.unlock();
try {
loadJavaScriptFileInContext(vocbase, file, context, builder);
} catch (...) {
guard.lock();
_idleContexts.push_back(context);
throw;
}
// and re-insert it after we are done
guard.lock();
_idleContexts.push_back(context);
} else {
LOG_TOPIC(WARN, Logger::V8) << "v8 context #" << context->id() << " has disappeared";
}
}
}
if (builder != nullptr) {
builder->close();
}
}
void V8DealerFeature::startGarbageCollection() {
TRI_ASSERT(_gcThread == nullptr);
_gcThread.reset(new V8GcThread(this));
_gcThread->start();
_gcFinished = false;
}
void V8DealerFeature::prepareLockedContext(TRI_vocbase_t* vocbase,
V8Context* context,
bool allowUseDatabase) {
TRI_ASSERT(vocbase != nullptr);
// when we get here, we should have a context and an isolate
context->assertLocked();
auto isolate = context->_isolate;
{
v8::HandleScope scope(isolate);
auto localContext = v8::Local<v8::Context>::New(isolate, context->_context);
localContext->Enter();
{
v8::Context::Scope contextScope(localContext);
context->assertLocked();
TRI_GET_GLOBALS();
// initialize the context data
v8g->_query = nullptr;
v8g->_vocbase = vocbase;
v8g->_allowUseDatabase = allowUseDatabase;
try {
LOG_TOPIC(TRACE, arangodb::Logger::V8) << "entering V8 context #" << context->id();
context->handleGlobalContextMethods();
} catch (...) {
// ignore errors here
}
}
}
}
/// @brief forceContext == -1 means that any free context may be
/// picked, or a new one will be created if we have not exceeded
/// the maximum number of contexts
/// forceContext == -2 means that any free context may be picked,
/// or a new one will be created if we have not exceeded or exactly
/// reached the maximum number of contexts. this can be used to
/// force the creation of another context for high priority tasks
/// forceContext >= 0 means picking the context with that exact id
V8Context* V8DealerFeature::enterContext(TRI_vocbase_t* vocbase,
bool allowUseDatabase,
ssize_t forceContext) {
TRI_ASSERT(vocbase != nullptr);
if (_stopping) {
return nullptr;
}
if (!vocbase->use()) {
return nullptr;
}
TimedAction exitWhenNoContext([](double waitTime) {
LOG_TOPIC(WARN, arangodb::Logger::V8) << "giving up waiting for unused V8 context after " << Logger::FIXED(waitTime) << " s";
}, 60);
V8Context* context = nullptr;
// this is for TESTING / DEBUGGING / INIT only
if (forceContext >= 0) {
size_t id = static_cast<size_t>(forceContext);
while (!_stopping) {
{
CONDITION_LOCKER(guard, _contextCondition);
if (_stopping) {
break;
}
for (auto it = _idleContexts.begin(); it != _idleContexts.end(); ++it) {
if ((*it)->id() == id) {
context = (*it);
_idleContexts.erase(it);
_busyContexts.emplace(context);
break;
}
}
if (context == nullptr) {
// still not found
for (auto it = _dirtyContexts.begin(); it != _dirtyContexts.end(); ++it) {
if ((*it)->id() == id) {
context = (*it);
_dirtyContexts.erase(it);
_busyContexts.emplace(context);
break;
}
}
}
if (context != nullptr) {
// found the context
TRI_ASSERT(guard.isLocked());
break;
}
// check if such context exists at all
bool found = false;
for (auto& it : _contexts) {
if (it->id() == id) {
found = true;
break;
}
}
if (!found) {
vocbase->release();
LOG_TOPIC(WARN, arangodb::Logger::V8) << "specified V8 context #" << id << " not found";
return nullptr;
}
}
LOG_TOPIC(DEBUG, arangodb::Logger::V8) << "waiting for V8 context #" << id << " to become available";
std::this_thread::sleep_for(std::chrono::microseconds(50 * 1000));
}
if (context == nullptr) {
vocbase->release();
return nullptr;
}
}
// look for a free context
else {
CONDITION_LOCKER(guard, _contextCondition);
while (_idleContexts.empty() && !_stopping) {
TRI_ASSERT(guard.isLocked());
LOG_TOPIC(TRACE, arangodb::Logger::V8) << "waiting for unused V8 context";
if (!_dirtyContexts.empty()) {
// we'll use a dirty context in this case
_idleContexts.push_back(_dirtyContexts.back());
_dirtyContexts.pop_back();
break;
}
bool contextLimitNotExceeded =
((_contexts.size() + _nrInflightContexts < _nrMaxContexts) ||
(forceContext == ANY_CONTEXT_OR_PRIORITY && (_contexts.size() + _nrInflightContexts <= _nrMaxContexts)));
if (contextLimitNotExceeded &&
_dynamicContextCreationBlockers == 0 &&
!MaxMapCountFeature::isNearMaxMappings()) {
++_nrInflightContexts;
TRI_ASSERT(guard.isLocked());
guard.unlock();
try {
LOG_TOPIC(DEBUG, Logger::V8) << "creating additional V8 context";
context = addContext();
} catch (...) {
guard.lock();
// clean up state
--_nrInflightContexts;
throw;
}
// must re-lock
TRI_ASSERT(!guard.isLocked());
guard.lock();
--_nrInflightContexts;
try {
_contexts.push_back(context);
} catch (...) {
// oops
delete context;
context = nullptr;
continue;
}
TRI_ASSERT(guard.isLocked());
try {
_idleContexts.push_back(context);
LOG_TOPIC(DEBUG, Logger::V8) << "created additional V8 context #" << context->id() << ", number of contexts is now " << _contexts.size();
} catch (...) {
TRI_ASSERT(!_contexts.empty());
_contexts.pop_back();
TRI_ASSERT(context != nullptr);
delete context;
}
guard.broadcast();
continue;
}
{
JobGuard jobGuard(SchedulerFeature::SCHEDULER);
jobGuard.block();
TRI_ASSERT(guard.isLocked());
guard.wait(100000);
}
if (exitWhenNoContext.tick()) {
vocbase->release();
return nullptr;
}
}
TRI_ASSERT(guard.isLocked());
// in case we are in the shutdown phase, do not enter a context!
// the context might have been deleted by the shutdown
if (_stopping) {
vocbase->release();
return nullptr;
}
TRI_ASSERT(!_idleContexts.empty());
context = _idleContexts.back();
LOG_TOPIC(TRACE, arangodb::Logger::V8) << "found unused V8 context #" << context->id();
TRI_ASSERT(context != nullptr);
_idleContexts.pop_back();
// should not fail because we reserved enough space beforehand
_busyContexts.emplace(context);
}
TRI_ASSERT(context != nullptr);
context->lockAndEnter();
context->assertLocked();
prepareLockedContext(vocbase, context, allowUseDatabase);
return context;
}
void V8DealerFeature::exitContextInternal(V8Context* context) {
TRI_DEFER(context->unlockAndExit());
cleanupLockedContext(context);
}
void V8DealerFeature::cleanupLockedContext(V8Context* context) {
TRI_ASSERT(context != nullptr);
LOG_TOPIC(TRACE, arangodb::Logger::V8) << "leaving V8 context #" << context->id();
auto isolate = context->_isolate;
TRI_ASSERT(isolate != nullptr);
context->assertLocked();
bool canceled = false;
if (V8PlatformFeature::isOutOfMemory(isolate)) {
static double const availableTime = 300.0;
v8::HandleScope scope(isolate);
{
auto localContext =
v8::Local<v8::Context>::New(isolate, context->_context);
localContext->Enter();
{
v8::Context::Scope contextScope(localContext);
TRI_RunGarbageCollectionV8(isolate, availableTime);
}
// needs to be reset after the garbage collection
V8PlatformFeature::resetOutOfMemory(isolate);
localContext->Exit();
}
}
// update data for later garbage collection
{
TRI_GET_GLOBALS();
context->_hasActiveExternals = v8g->hasActiveExternals();
TRI_vocbase_t* vocbase = v8g->_vocbase;
TRI_ASSERT(vocbase != nullptr);
// release last recently used vocbase
vocbase->release();
// check for cancelation requests
canceled = v8g->_canceled;
v8g->_canceled = false;
}
// check if we need to execute global context methods
bool const runGlobal = context->hasGlobalMethodsQueued();
{
v8::HandleScope scope(isolate);
// if the execution was canceled, we need to cleanup
if (canceled) {
context->handleCancelationCleanup();
}
// run global context methods
if (runGlobal) {
context->assertLocked();
try {
context->handleGlobalContextMethods();
} catch (...) {
// ignore errors here
}
}
TRI_GET_GLOBALS();
// reset the context data; gc should be able to run without it
v8g->_query = nullptr;
v8g->_vocbase = nullptr;
v8g->_allowUseDatabase = false;
// now really exit
auto localContext = v8::Local<v8::Context>::New(isolate, context->_context);
localContext->Exit();
}
}
void V8DealerFeature::exitContext(V8Context* context) {
cleanupLockedContext(context);
V8GcThread* gc = static_cast<V8GcThread*>(_gcThread.get());
if (gc != nullptr) {
// default is no garbage collection
bool performGarbageCollection = false;
bool forceGarbageCollection = false;
// postpone garbage collection for standard contexts
double lastGc = gc->getLastGcStamp();
if (context->_lastGcStamp + _gcFrequency < lastGc) {
performGarbageCollection = true;
if (context->_lastGcStamp + 30 * _gcFrequency < lastGc) {
// force the GC, so that it happens eventually
forceGarbageCollection = true;
LOG_TOPIC(TRACE, arangodb::Logger::V8) << "V8 context #" << context->id()
<< " has reached GC timeout threshold and will be forced into GC";
} else {
LOG_TOPIC(TRACE, arangodb::Logger::V8) << "V8 context #" << context->id()
<< " has reached GC timeout threshold and will be scheduled for GC";
}
} else if (context->invocationsSinceLastGc() >= _gcInterval) {
LOG_TOPIC(TRACE, arangodb::Logger::V8)
<< "V8 context #" << context->id() << " has reached maximum number of requests and will "
"be scheduled for GC";
performGarbageCollection = true;
}
context->unlockAndExit();
CONDITION_LOCKER(guard, _contextCondition);
if (performGarbageCollection && (forceGarbageCollection || !_idleContexts.empty())) {
// only add the context to the dirty list if there is at least one other
// free context
// note that re-adding the context here should not fail as we reserved
// enough room for all contexts during startup
_dirtyContexts.emplace_back(context);
} else {
// note that re-adding the context here should not fail as we reserved
// enough room for all contexts during startup
_idleContexts.emplace_back(context);
}
_busyContexts.erase(context);
LOG_TOPIC(TRACE, arangodb::Logger::V8) << "returned dirty V8 context #" << context->id();
guard.broadcast();
} else {
context->unlockAndExit();
CONDITION_LOCKER(guard, _contextCondition);
_busyContexts.erase(context);
// note that re-adding the context here should not fail as we reserved
// enough room for all contexts during startup
_idleContexts.emplace_back(context);
LOG_TOPIC(TRACE, arangodb::Logger::V8) << "returned dirty V8 context #" << context->id() << " back into free";
guard.broadcast();
}
}
void V8DealerFeature::defineContextUpdate(
std::function<void(v8::Isolate*, v8::Handle<v8::Context>, size_t)> func,
TRI_vocbase_t* vocbase) {
_contextUpdates.emplace_back(func, vocbase);
}
// apply context update is only run on contexts that no other
// threads can see (yet)
void V8DealerFeature::applyContextUpdate(V8Context* context) {
for (auto& p : _contextUpdates) {
auto vocbase = p.second;
if (vocbase == nullptr) {
vocbase = DatabaseFeature::DATABASE->systemDatabase();
}
if (!vocbase->use()) {
// oops
continue;
}
context->lockAndEnter();
prepareLockedContext(vocbase, context, true);
TRI_DEFER(exitContextInternal(context));
{
v8::HandleScope scope(context->_isolate);
auto localContext =
v8::Local<v8::Context>::New(context->_isolate, context->_context);
localContext->Enter();
{
v8::Context::Scope contextScope(localContext);
p.first(context->_isolate, localContext, context->id());
}
localContext->Exit();
}
LOG_TOPIC(TRACE, arangodb::Logger::V8) << "updated V8 context #" << context->id();
}
}
void V8DealerFeature::shutdownContexts() {
_stopping = true;
// wait for all contexts to finish
{
CONDITION_LOCKER(guard, _contextCondition);
guard.broadcast();
for (size_t n = 0; n < 10 * 5; ++n) {
if (_busyContexts.empty()) {
LOG_TOPIC(DEBUG, arangodb::Logger::V8) << "no busy V8 contexts";
break;
}
LOG_TOPIC(DEBUG, arangodb::Logger::V8) << "waiting for busy V8 contexts (" << _busyContexts.size()
<< ") to finish ";
guard.wait(100 * 1000);
}
}
// send all busy contexts a terminate signal
{
CONDITION_LOCKER(guard, _contextCondition);
for (auto& it : _busyContexts) {
LOG_TOPIC(WARN, arangodb::Logger::V8) << "sending termination signal to V8 context #" << it->id();
v8::V8::TerminateExecution(it->_isolate);
}
}
// wait for one minute
{
CONDITION_LOCKER(guard, _contextCondition);
for (size_t n = 0; n < 10 * 60; ++n) {
if (_busyContexts.empty()) {
break;
}
guard.wait(100000);
}
}
if (!_busyContexts.empty()) {
LOG_TOPIC(FATAL, arangodb::Logger::V8) << "cannot shutdown V8 contexts";
FATAL_ERROR_EXIT();
}
// stop GC thread
if (_gcThread != nullptr) {
LOG_TOPIC(DEBUG, arangodb::Logger::V8) << "waiting for V8 GC thread to finish action";
_gcThread->beginShutdown();
// wait until garbage collector thread is done
while (!_gcFinished) {
std::this_thread::sleep_for(std::chrono::microseconds(10000));
}
LOG_TOPIC(DEBUG, arangodb::Logger::V8) << "commanding V8 GC thread to terminate";
}
// shutdown all instances
{
CONDITION_LOCKER(guard, _contextCondition);
for (auto& context : _contexts) {
shutdownContext(context);
}
_contexts.clear();
}
LOG_TOPIC(DEBUG, arangodb::Logger::V8) << "V8 contexts are shut down";
}
V8Context* V8DealerFeature::pickFreeContextForGc() {
int const n = static_cast<int>(_idleContexts.size());
if (n == 0) {
// this is easy...
return nullptr;
}
V8GcThread* gc = static_cast<V8GcThread*>(_gcThread.get());
TRI_ASSERT(gc != nullptr);
// we got more than 1 context to clean up, pick the one with the "oldest" GC
// stamp
int pickedContextNr =
-1; // index of context with lowest GC stamp, -1 means "none"
for (int i = n - 1; i > 0; --i) {
// check if there's actually anything to clean up in the context
if (_idleContexts[i]->invocationsSinceLastGc() < 50 &&
!_idleContexts[i]->_hasActiveExternals) {
continue;
}
// compare last GC stamp
if (pickedContextNr == -1 ||
_idleContexts[i]->_lastGcStamp <=
_idleContexts[pickedContextNr]->_lastGcStamp) {
pickedContextNr = i;
}
}
// we now have the context to clean up in pickedContextNr
if (pickedContextNr == -1) {
// no context found
return nullptr;
}
// this is the context to clean up
V8Context* context = _idleContexts[pickedContextNr];
TRI_ASSERT(context != nullptr);
// now compare its last GC timestamp with the last global GC stamp
if (context->_lastGcStamp + _gcFrequency >= gc->getLastGcStamp()) {
// no need yet to clean up the context
return nullptr;
}
// we'll pop the context from the vector. the context might be at
// any position in the vector so we need to move the other elements
// around
if (n > 1) {
for (int i = pickedContextNr; i < n - 1; ++i) {
_idleContexts[i] = _idleContexts[i + 1];
}
}
_idleContexts.pop_back();
return context;
}
V8Context* V8DealerFeature::buildContext(size_t id) {
V8PlatformFeature* v8platform =
application_features::ApplicationServer::getFeature<V8PlatformFeature>(
"V8Platform");
TRI_ASSERT(v8platform != nullptr);
// create isolate
v8::Isolate* isolate = v8platform->createIsolate();
TRI_ASSERT(isolate != nullptr);
// pass isolate to a new context
auto context = std::make_unique<V8Context>(id, isolate);
try {
// this guard will lock and enter the isolate
// and automatically exit and unlock it when it runs out of scope
V8ContextEntryGuard contextGuard(context.get());
v8::HandleScope scope(isolate);
v8::Handle<v8::ObjectTemplate> global = v8::ObjectTemplate::New(isolate);
v8::Persistent<v8::Context> persistentContext;
persistentContext.Reset(isolate, v8::Context::New(isolate, 0, global));
auto localContext = v8::Local<v8::Context>::New(isolate, persistentContext);
localContext->Enter();
{
v8::Context::Scope contextScope(localContext);
TRI_CreateV8Globals(isolate);
context->_context.Reset(context->_isolate, localContext);
if (context->_context.IsEmpty()) {
LOG_TOPIC(FATAL, arangodb::Logger::V8) << "cannot initialize V8 engine";
FATAL_ERROR_EXIT();
}
v8::Handle<v8::Object> globalObj = localContext->Global();
globalObj->Set(TRI_V8_ASCII_STRING(isolate, "GLOBAL"), globalObj);
globalObj->Set(TRI_V8_ASCII_STRING(isolate, "global"), globalObj);
globalObj->Set(TRI_V8_ASCII_STRING(isolate, "root"), globalObj);
std::string modules = "";
std::string sep = "";
std::vector<std::string> directories;
directories.insert(directories.end(), _moduleDirectory.begin(),
_moduleDirectory.end());
directories.emplace_back(_startupDirectory);
for (auto directory : directories) {
modules += sep;
sep = ";";
modules += FileUtils::buildFilename(directory, "server/modules") + sep +
FileUtils::buildFilename(directory, "common/modules") + sep +
FileUtils::buildFilename(directory, "node");
}
TRI_InitV8UserFunctions(isolate, localContext);
TRI_InitV8UserStructures(isolate, localContext);
TRI_InitV8Buffer(isolate, localContext);
TRI_InitV8Utils(isolate, localContext, _startupDirectory, modules);
TRI_InitV8DebugUtils(isolate, localContext);
TRI_InitV8Shell(isolate, localContext);
{
v8::HandleScope scope(isolate);
TRI_AddGlobalVariableVocbase(isolate,
TRI_V8_ASCII_STRING(isolate, "APP_PATH"),
TRI_V8_STD_STRING(isolate, _appPath));
for (auto j : _definedBooleans) {
localContext->Global()->ForceSet(TRI_V8_STD_STRING(isolate, j.first),
v8::Boolean::New(isolate, j.second),
v8::ReadOnly);
}
for (auto j : _definedDoubles) {
localContext->Global()->ForceSet(TRI_V8_STD_STRING(isolate, j.first),
v8::Number::New(isolate, j.second),
v8::ReadOnly);
}
for (auto const& j : _definedStrings) {
localContext->Global()->ForceSet(TRI_V8_STD_STRING(isolate, j.first),
TRI_V8_STD_STRING(isolate, j.second),
v8::ReadOnly);
}
}
}
// and return from the context
localContext->Exit();
} catch (...) {
LOG_TOPIC(WARN, Logger::V8) << "caught exception during context initialization";
v8platform->disposeIsolate(isolate);
throw;
}
// some random delay value to add as an initial garbage collection offset
// this avoids collecting all contexts at the very same time
double const randomWait =
static_cast<double>(RandomGenerator::interval(0, 60));
// initialize garbage collection for context
context->_hasActiveExternals = true;
context->_lastGcStamp = TRI_microtime() + randomWait;
LOG_TOPIC(TRACE, arangodb::Logger::V8) << "initialized V8 context #" << id;
return context.release();
}
V8DealerFeature::stats V8DealerFeature::getCurrentContextNumbers() {
CONDITION_LOCKER(guard, _contextCondition);
return {
_contexts.size(),
_busyContexts.size(),
_dirtyContexts.size(),
_idleContexts.size(),
_nrMaxContexts
};
}
bool V8DealerFeature::loadJavaScriptFileInContext(TRI_vocbase_t* vocbase,
std::string const& file, V8Context* context,
VPackBuilder* builder) {
TRI_ASSERT(vocbase != nullptr);
TRI_ASSERT(context != nullptr);
if (_stopping) {
return false;
}
if (!vocbase->use()) {
return false;
}
context->lockAndEnter();
prepareLockedContext(vocbase, context, true);
TRI_DEFER(exitContextInternal(context));
try {
loadJavaScriptFileInternal(file, context, builder);
} catch (...) {
LOG_TOPIC(WARN, Logger::V8) << "caught exception while executing JavaScript file '" << file << "' in context #" << context->id();
throw;
}
return true;
}
void V8DealerFeature::loadJavaScriptFileInternal(std::string const& file, V8Context* context, VPackBuilder* builder) {
v8::HandleScope scope(context->_isolate);
auto localContext =
v8::Local<v8::Context>::New(context->_isolate, context->_context);
localContext->Enter();
{
v8::Context::Scope contextScope(localContext);
switch (
_startupLoader.loadScript(context->_isolate, localContext, file, builder)) {
case JSLoader::eSuccess:
LOG_TOPIC(TRACE, arangodb::Logger::V8) << "loaded JavaScript file '" << file << "'";
break;
case JSLoader::eFailLoad:
LOG_TOPIC(FATAL, arangodb::Logger::V8) << "cannot load JavaScript file '" << file << "'";
FATAL_ERROR_EXIT();
break;
case JSLoader::eFailExecute:
LOG_TOPIC(FATAL, arangodb::Logger::V8) << "error during execution of JavaScript file '" << file
<< "'";
FATAL_ERROR_EXIT();
break;
}
}
LOG_TOPIC(TRACE, arangodb::Logger::V8) << "loaded Javascript file '" << file << "' for V8 context #" << context->id();
}
void V8DealerFeature::shutdownContext(V8Context* context) {
TRI_ASSERT(context != nullptr);
LOG_TOPIC(TRACE, arangodb::Logger::V8) << "shutting down V8 context #" << context->id();
auto isolate = context->_isolate;
{
// this guard will lock and enter the isolate
// and automatically exit and unlock it when it runs out of scope
V8ContextEntryGuard contextGuard(context);
v8::HandleScope scope(isolate);
auto localContext = v8::Local<v8::Context>::New(isolate, context->_context);
localContext->Enter();
{
v8::Context::Scope contextScope(localContext);
TRI_VisitActions([&isolate](TRI_action_t* action) {
action->visit(isolate);
});
double availableTime = 30.0;
if (RUNNING_ON_VALGRIND) {
// running under Valgrind
availableTime *= 10;
int tries = 0;
while (tries++ < 10 &&
TRI_RunGarbageCollectionV8(isolate, availableTime)) {
if (tries > 3) {
LOG_TOPIC(WARN, arangodb::Logger::V8) << "waiting for garbage v8 collection to end";
}
}
} else {
TRI_RunGarbageCollectionV8(isolate, availableTime);
}
TRI_GET_GLOBALS();
if (v8g != nullptr) {
if (v8g->_transactionContext != nullptr) {
delete static_cast<transaction::V8Context*>(v8g->_transactionContext);
v8g->_transactionContext = nullptr;
}
delete v8g;
}
}
localContext->Exit();
}
context->_context.Reset();
application_features::ApplicationServer::getFeature<V8PlatformFeature>(
"V8Platform")->disposeIsolate(isolate);
LOG_TOPIC(TRACE, arangodb::Logger::V8) << "closed V8 context #" << context->id();
delete context;
}
V8ContextDealerGuard::V8ContextDealerGuard(Result& res, v8::Isolate*& isolate, TRI_vocbase_t* vocbase, bool allowModification)
: _isolate(isolate)
, _context(nullptr)
, _active(isolate ? false : true)
{
if (_active) {
if(!vocbase){
res.reset(TRI_ERROR_INTERNAL, "V8ContextDealerGuard - no vocbase provided");
return;
}
_context = V8DealerFeature::DEALER->enterContext(vocbase, allowModification);
if (!_context) {
res.reset(TRI_ERROR_INTERNAL, "V8ContextDealerGuard - could not acquire context");
return;
}
isolate = _context->_isolate;
}
}
V8ContextDealerGuard::~V8ContextDealerGuard() {
if (_active && _context) {
try {
V8DealerFeature::DEALER->exitContext(_context);
}
catch (...) {}
_isolate = nullptr;
}
}
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