gecko-dev/xpcom/base/nsExceptionService.cpp

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2012-05-21 11:12:37 +00:00
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "mozilla/Attributes.h"
#include "nsISupports.h"
#include "nsExceptionService.h"
#include "nsIServiceManager.h"
#include "nsCOMPtr.h"
#include "prthread.h"
#include "mozilla/Services.h"
using namespace mozilla;
static const unsigned BAD_TLS_INDEX = (unsigned) -1;
#define CHECK_SERVICE_USE_OK() if (!sLock) return NS_ERROR_NOT_INITIALIZED
#define CHECK_MANAGER_USE_OK() if (!mService || !nsExceptionService::sLock) return NS_ERROR_NOT_INITIALIZED
// A key for our registered module providers hashtable
class nsProviderKey : public nsHashKey {
protected:
uint32_t mKey;
public:
nsProviderKey(uint32_t key) : mKey(key) {}
uint32_t HashCode(void) const {
return mKey;
}
bool Equals(const nsHashKey *aKey) const {
return mKey == ((const nsProviderKey *) aKey)->mKey;
}
nsHashKey *Clone() const {
return new nsProviderKey(mKey);
}
uint32_t GetValue() { return mKey; }
};
/** Exception Manager definition **/
class nsExceptionManager MOZ_FINAL : public nsIExceptionManager
{
public:
NS_DECL_ISUPPORTS
NS_DECL_NSIEXCEPTIONMANAGER
nsExceptionManager(nsExceptionService *svc);
/* additional members */
nsCOMPtr<nsIException> mCurrentException;
nsExceptionManager *mNextThread; // not ref-counted.
nsExceptionService *mService; // not ref-counted
#ifdef DEBUG
static int32_t totalInstances;
#endif
private:
~nsExceptionManager();
};
#ifdef DEBUG
int32_t nsExceptionManager::totalInstances = 0;
#endif
// Note this object is single threaded - the service itself ensures
// one per thread.
// An exception if the destructor, which may be called on
// the thread shutting down xpcom
NS_IMPL_THREADSAFE_ISUPPORTS1(nsExceptionManager, nsIExceptionManager)
nsExceptionManager::nsExceptionManager(nsExceptionService *svc) :
mNextThread(nullptr),
mService(svc)
{
/* member initializers and constructor code */
#ifdef DEBUG
PR_ATOMIC_INCREMENT(&totalInstances);
#endif
}
nsExceptionManager::~nsExceptionManager()
{
/* destructor code */
#ifdef DEBUG
PR_ATOMIC_DECREMENT(&totalInstances);
#endif // DEBUG
}
/* void setCurrentException (in nsIException error); */
NS_IMETHODIMP nsExceptionManager::SetCurrentException(nsIException *error)
{
CHECK_MANAGER_USE_OK();
mCurrentException = error;
return NS_OK;
}
/* nsIException getCurrentException (); */
NS_IMETHODIMP nsExceptionManager::GetCurrentException(nsIException **_retval)
{
CHECK_MANAGER_USE_OK();
*_retval = mCurrentException;
NS_IF_ADDREF(*_retval);
return NS_OK;
}
/* nsIException getExceptionFromProvider( in nsresult rc, in nsIException defaultException); */
NS_IMETHODIMP nsExceptionManager::GetExceptionFromProvider(nsresult rc, nsIException * defaultException, nsIException **_retval)
{
CHECK_MANAGER_USE_OK();
// Just delegate back to the service with the provider map.
return mService->GetExceptionFromProvider(rc, defaultException, _retval);
}
/* The Exception Service */
unsigned nsExceptionService::tlsIndex = BAD_TLS_INDEX;
Mutex *nsExceptionService::sLock = nullptr;
nsExceptionManager *nsExceptionService::firstThread = nullptr;
#ifdef DEBUG
int32_t nsExceptionService::totalInstances = 0;
#endif
NS_IMPL_THREADSAFE_ISUPPORTS3(nsExceptionService,
nsIExceptionService,
nsIExceptionManager,
nsIObserver)
nsExceptionService::nsExceptionService()
: mProviders(4, true) /* small, thread-safe hashtable */
{
#ifdef DEBUG
if (PR_ATOMIC_INCREMENT(&totalInstances)!=1) {
NS_ERROR("The nsExceptionService is a singleton!");
}
#endif
/* member initializers and constructor code */
if (tlsIndex == BAD_TLS_INDEX) {
PRStatus status;
status = PR_NewThreadPrivateIndex( &tlsIndex, ThreadDestruct );
NS_ASSERTION(status==0, "ScriptErrorService could not allocate TLS storage.");
}
sLock = new Mutex("nsExceptionService.sLock");
// observe XPCOM shutdown.
nsCOMPtr<nsIObserverService> observerService =
mozilla::services::GetObserverService();
NS_ASSERTION(observerService, "Could not get observer service!");
if (observerService)
observerService->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);
}
nsExceptionService::~nsExceptionService()
{
Shutdown();
/* destructor code */
#ifdef DEBUG
PR_ATOMIC_DECREMENT(&totalInstances);
#endif
}
/*static*/
void nsExceptionService::ThreadDestruct( void *data )
{
if (!sLock) {
NS_WARNING("nsExceptionService ignoring thread destruction after shutdown");
return;
}
DropThread( (nsExceptionManager *)data );
}
void nsExceptionService::Shutdown()
{
mProviders.Reset();
if (sLock) {
DropAllThreads();
delete sLock;
sLock = nullptr;
}
PR_SetThreadPrivate(tlsIndex, nullptr);
}
/* void setCurrentException (in nsIException error); */
NS_IMETHODIMP nsExceptionService::SetCurrentException(nsIException *error)
{
CHECK_SERVICE_USE_OK();
nsCOMPtr<nsIExceptionManager> sm;
nsresult nr = GetCurrentExceptionManager(getter_AddRefs(sm));
if (NS_FAILED(nr))
return nr;
return sm->SetCurrentException(error);
}
/* nsIException getCurrentException (); */
NS_IMETHODIMP nsExceptionService::GetCurrentException(nsIException **_retval)
{
CHECK_SERVICE_USE_OK();
nsCOMPtr<nsIExceptionManager> sm;
nsresult nr = GetCurrentExceptionManager(getter_AddRefs(sm));
if (NS_FAILED(nr))
return nr;
return sm->GetCurrentException(_retval);
}
/* nsIException getExceptionFromProvider( in nsresult rc, in nsIException defaultException); */
NS_IMETHODIMP nsExceptionService::GetExceptionFromProvider(nsresult rc,
nsIException * defaultException, nsIException **_retval)
{
CHECK_SERVICE_USE_OK();
return DoGetExceptionFromProvider(rc, defaultException, _retval);
}
/* readonly attribute nsIExceptionManager currentExceptionManager; */
NS_IMETHODIMP nsExceptionService::GetCurrentExceptionManager(nsIExceptionManager * *aCurrentScriptManager)
{
CHECK_SERVICE_USE_OK();
nsExceptionManager *mgr = (nsExceptionManager *)PR_GetThreadPrivate(tlsIndex);
if (mgr == nullptr) {
// Stick the new exception object in with no reference count.
mgr = new nsExceptionManager(this);
PR_SetThreadPrivate(tlsIndex, mgr);
// The reference count is held in the thread-list
AddThread(mgr);
}
*aCurrentScriptManager = mgr;
NS_ADDREF(*aCurrentScriptManager);
return NS_OK;
}
/* void registerErrorProvider (in nsIExceptionProvider provider, in uint32_t moduleCode); */
NS_IMETHODIMP nsExceptionService::RegisterExceptionProvider(nsIExceptionProvider *provider, uint32_t errorModule)
{
CHECK_SERVICE_USE_OK();
nsProviderKey key(errorModule);
if (mProviders.Put(&key, provider)) {
NS_WARNING("Registration of exception provider overwrote another provider with the same module code!");
}
return NS_OK;
}
/* void unregisterErrorProvider (in nsIExceptionProvider provider, in uint32_t errorModule); */
NS_IMETHODIMP nsExceptionService::UnregisterExceptionProvider(nsIExceptionProvider *provider, uint32_t errorModule)
{
CHECK_SERVICE_USE_OK();
nsProviderKey key(errorModule);
if (!mProviders.Remove(&key)) {
NS_WARNING("Attempt to unregister an unregistered exception provider!");
return NS_ERROR_UNEXPECTED;
}
return NS_OK;
}
// nsIObserver
NS_IMETHODIMP nsExceptionService::Observe(nsISupports *aSubject, const char *aTopic, const PRUnichar *someData)
{
Shutdown();
return NS_OK;
}
nsresult
nsExceptionService::DoGetExceptionFromProvider(nsresult errCode,
nsIException * defaultException,
nsIException **_exc)
{
// Check for an existing exception
nsresult nr = GetCurrentException(_exc);
if (NS_SUCCEEDED(nr) && *_exc) {
(*_exc)->GetResult(&nr);
// If it matches our result then use it
if (nr == errCode)
return NS_OK;
NS_RELEASE(*_exc);
}
nsProviderKey key(NS_ERROR_GET_MODULE(errCode));
nsCOMPtr<nsIExceptionProvider> provider =
dont_AddRef((nsIExceptionProvider *)mProviders.Get(&key));
// No provider so we'll return the default exception
if (!provider) {
*_exc = defaultException;
NS_IF_ADDREF(*_exc);
return NS_OK;
}
return provider->GetException(errCode, defaultException, _exc);
}
// thread management
/*static*/ void nsExceptionService::AddThread(nsExceptionManager *thread)
{
MutexAutoLock lock(*sLock);
thread->mNextThread = firstThread;
firstThread = thread;
NS_ADDREF(thread);
}
/*static*/ void nsExceptionService::DoDropThread(nsExceptionManager *thread)
{
nsExceptionManager **emp = &firstThread;
while (*emp != thread) {
NS_ABORT_IF_FALSE(*emp, "Could not find the thread to drop!");
emp = &(*emp)->mNextThread;
}
*emp = thread->mNextThread;
NS_RELEASE(thread);
}
/*static*/ void nsExceptionService::DropThread(nsExceptionManager *thread)
{
MutexAutoLock lock(*sLock);
DoDropThread(thread);
}
/*static*/ void nsExceptionService::DropAllThreads()
{
MutexAutoLock lock(*sLock);
while (firstThread)
DoDropThread(firstThread);
}