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|
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// CancelableRequestProviders and Consumers work together to make requests that
// execute on a background thread in the provider and return data to the
// consumer. These classes collaborate to keep a list of open requests and to
// make sure that requests do not outlive either of the objects involved in the
// transaction.
//
// If you do not need to return data to the consumer, do not use this system,
// just use the regular Task/RunnableMethod stuff.
//
// The CancelableRequest object is used internally to each provider to track
// request data and callback information.
//
// Example consumer calling |StartRequest| on a frontend service:
//
// class MyClass {
// void MakeRequest() {
// frontend_service->StartRequest(
// some_input1, some_input2,
// &callback_consumer_,
// base::Bind(&MyClass:RequestComplete, base::Unretained(this)));
// // StartRequest() returns a Handle which may be retained for use with
// // CancelRequest() if required, e.g. in MyClass's destructor.
// }
//
// void RequestComplete(int status) {
// ...
// }
//
// private:
// CancelableRequestConsumer callback_consumer_;
// };
//
//
// Example frontend provider. It receives requests and forwards them to the
// backend on another thread:
//
// class Frontend : public CancelableRequestProvider {
// typedef Callback1<int>::Type RequestCallbackType;
//
// Handle StartRequest(int some_input1, int some_input2,
// CancelableRequestConsumerBase* consumer,
// RequestCallbackType* callback) {
// scoped_refptr<CancelableRequest<RequestCallbackType> > request(
// new CancelableRequest<RequestCallbackType>(callback));
// AddRequest(request, consumer);
//
// // Send the parameters and the request to the backend thread.
// backend_thread_->PostTask(
// FROM_HERE,
// base::Bind(&Backend::DoRequest, backend_, request,
// some_input1, some_input2));
//
// // The handle will have been set by AddRequest.
// return request->handle();
// }
// };
//
//
// Example backend provider that does work and dispatches the callback back
// to the original thread. Note that we need to pass it as a scoped_refptr so
// that the object will be kept alive if the request is canceled (releasing
// the provider's reference to it).
//
// class Backend {
// void DoRequest(
// scoped_refptr< CancelableRequest<Frontend::RequestCallbackType> >
// request,
// int some_input1, int some_input2) {
// if (request->canceled())
// return;
//
// ... do your processing ...
//
// // Depending on your typedefs, one of these two forms will be more
// // convenient:
// request->ForwardResult(Tuple1<int>(return_value));
//
// // -- or -- (inferior in this case)
// request->ForwardResult(Frontend::RequestCallbackType::TupleType(
// return_value));
// }
// };
#ifndef CHROME_BROWSER_COMMON_CANCELABLE_REQUEST_H_
#define CHROME_BROWSER_COMMON_CANCELABLE_REQUEST_H_
#include <map>
#include <vector>
#include "base/basictypes.h"
#include "base/bind.h"
#include "base/callback.h"
#include "base/callback_internal.h"
#include "base/logging.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "base/message_loop.h"
#include "base/synchronization/cancellation_flag.h"
#include "base/synchronization/lock.h"
#include "build/build_config.h"
class CancelableRequestBase;
class CancelableRequestConsumerBase;
// CancelableRequestProvider --------------------------------------------------
//
// This class is threadsafe. Requests may be added or canceled from any thread,
// but a task must only be canceled from the same thread it was initially run
// on.
//
// It is intended that providers inherit from this class to provide the
// necessary functionality.
class CancelableRequestProvider {
public:
// Identifies a specific request from this provider.
typedef int Handle;
CancelableRequestProvider();
// Called by the enduser of the request to cancel it. This MUST be called on
// the same thread that originally issued the request (which is also the same
// thread that would have received the callback if it was not canceled).
// handle must be for a valid pending (not yet complete or cancelled) request.
void CancelRequest(Handle handle);
protected:
virtual ~CancelableRequestProvider();
// Adds a new request and initializes it. This is called by a derived class
// to add a new request. The request's Init() will be called (which is why
// the consumer is required. The handle to the new request is returned.
Handle AddRequest(CancelableRequestBase* request,
CancelableRequestConsumerBase* consumer);
// Called by the CancelableRequest when the request has executed. It will
// be removed from the list of pending requests (as opposed to canceling,
// which will also set some state on the request).
void RequestCompleted(Handle handle);
private:
typedef std::map<Handle, scoped_refptr<CancelableRequestBase> >
CancelableRequestMap;
// Only call this when you already have acquired pending_request_lock_.
void CancelRequestLocked(const CancelableRequestMap::iterator& item);
friend class CancelableRequestBase;
base::Lock pending_request_lock_;
// Lists all outstanding requests. Protected by the |lock_|.
CancelableRequestMap pending_requests_;
// The next handle value we will return. Protected by the |lock_|.
int next_handle_;
DISALLOW_COPY_AND_ASSIGN(CancelableRequestProvider);
};
// CancelableRequestConsumer --------------------------------------------------
//
// Classes wishing to make requests on a provider should have an instance of
// this class. Callers will need to pass a pointer to this consumer object
// when they make the request. It will automatically track any pending
// requests, and will automatically cancel them on destruction to prevent the
// accidental calling of freed memory.
//
// It is recommended to just have this class as a member variable since there
// is nothing to be gained by inheriting from it other than polluting your
// namespace.
//
// THIS CLASS IS NOT THREADSAFE (unlike the provider). You must make requests
// and get callbacks all from the same thread.
// Base class used to notify of new requests.
class CancelableRequestConsumerBase {
protected:
friend class CancelableRequestBase;
friend class CancelableRequestProvider;
virtual ~CancelableRequestConsumerBase() {
}
// Adds a new request to the list of requests that are being tracked. This
// is called by the provider when a new request is created.
virtual void OnRequestAdded(CancelableRequestProvider* provider,
CancelableRequestProvider::Handle handle) = 0;
// Removes the given request from the list of pending requests. Called
// by the CancelableRequest immediately after the callback has executed for a
// given request, and by the provider when a request is canceled.
virtual void OnRequestRemoved(CancelableRequestProvider* provider,
CancelableRequestProvider::Handle handle) = 0;
// Sent to provider before executing a callback.
virtual void WillExecute(CancelableRequestProvider* provider,
CancelableRequestProvider::Handle handle) = 0;
// Sent after executing a callback.
virtual void DidExecute(CancelableRequestProvider* provider,
CancelableRequestProvider::Handle handle) = 0;
};
// Template for clients to use. It allows them to associate random "client
// data" with a specific request. The default value for this type is 0.
// The type T should be small and easily copyable (like a pointer
// or an integer).
template<class T>
class CancelableRequestConsumerTSimple
: public CancelableRequestConsumerBase {
public:
CancelableRequestConsumerTSimple();
// Cancel any outstanding requests so that we do not get called back after we
// are destroyed. As these requests are removed, the providers will call us
// back on OnRequestRemoved, which will then update the list. To iterate
// successfully while the list is changing out from under us, we make a copy.
virtual ~CancelableRequestConsumerTSimple();
// Associates some random data with a specified request. The request MUST be
// outstanding, or it will assert. This is intended to be called immediately
// after a request is issued.
void SetClientData(CancelableRequestProvider* p,
CancelableRequestProvider::Handle h,
T client_data);
// Retrieves previously associated data for a specified request. The request
// MUST be outstanding, or it will assert. This is intended to be called
// during processing of a callback to retrieve extra data.
T GetClientData(CancelableRequestProvider* p,
CancelableRequestProvider::Handle h);
// Returns the data associated with the current request being processed. This
// is only valid during the time a callback is being processed.
T GetClientDataForCurrentRequest();
// Returns true if there are any pending requests.
bool HasPendingRequests() const;
// Returns the number of pending requests.
size_t PendingRequestCount() const;
// Cancels all requests outstanding.
void CancelAllRequests();
// Cancels all requests outstanding matching the client data.
void CancelAllRequestsForClientData(T client_data);
// Returns the handle for the first request that has the specified client data
// (in |handle|). Returns true if there is a request for the specified client
// data, false otherwise.
bool GetFirstHandleForClientData(T client_data,
CancelableRequestProvider::Handle* handle);
// Gets the client data for all pending requests.
void GetAllClientData(std::vector<T>* data);
protected:
struct PendingRequest {
PendingRequest(CancelableRequestProvider* p,
CancelableRequestProvider::Handle h)
: provider(p), handle(h) {
}
PendingRequest() : provider(NULL), handle(0) {}
// Comparison operator for stl.
bool operator<(const PendingRequest& other) const {
if (provider != other.provider)
return provider < other.provider;
return handle < other.handle;
}
bool is_valid() const { return provider != NULL; }
CancelableRequestProvider* provider;
CancelableRequestProvider::Handle handle;
};
typedef std::map<PendingRequest, T> PendingRequestList;
virtual T get_initial_t() const;
virtual void OnRequestAdded(CancelableRequestProvider* provider,
CancelableRequestProvider::Handle handle);
virtual void OnRequestRemoved(CancelableRequestProvider* provider,
CancelableRequestProvider::Handle handle);
virtual void WillExecute(CancelableRequestProvider* provider,
CancelableRequestProvider::Handle handle);
virtual void DidExecute(CancelableRequestProvider* provider,
CancelableRequestProvider::Handle handle);
// Lists all outstanding requests.
PendingRequestList pending_requests_;
// This is valid while processing a request and is used to identify the
// provider/handle of request.
PendingRequest current_request_;
};
template<class T>
CancelableRequestConsumerTSimple<T>::CancelableRequestConsumerTSimple() {
}
template<class T>
CancelableRequestConsumerTSimple<T>::~CancelableRequestConsumerTSimple() {
CancelAllRequests();
}
template<class T>
void CancelableRequestConsumerTSimple<T>::SetClientData(
CancelableRequestProvider* p,
CancelableRequestProvider::Handle h,
T client_data) {
PendingRequest request(p, h);
DCHECK(pending_requests_.find(request) != pending_requests_.end());
pending_requests_[request] = client_data;
}
template<class T>
T CancelableRequestConsumerTSimple<T>::GetClientData(
CancelableRequestProvider* p,
CancelableRequestProvider::Handle h) {
PendingRequest request(p, h);
DCHECK(pending_requests_.find(request) != pending_requests_.end());
return pending_requests_[request];
}
template<class T>
T CancelableRequestConsumerTSimple<T>::GetClientDataForCurrentRequest() {
DCHECK(current_request_.is_valid());
return GetClientData(current_request_.provider, current_request_.handle);
}
template<class T>
bool CancelableRequestConsumerTSimple<T>::HasPendingRequests() const {
return !pending_requests_.empty();
}
template<class T>
size_t CancelableRequestConsumerTSimple<T>::PendingRequestCount() const {
return pending_requests_.size();
}
template<class T>
void CancelableRequestConsumerTSimple<T>::CancelAllRequests() {
// TODO(atwilson): This code is not thread safe as it is called from the
// consumer thread (via the destructor) and accesses pending_requests_
// without acquiring the provider lock (http://crbug.com/85970).
PendingRequestList copied_requests(pending_requests_);
for (typename PendingRequestList::iterator i = copied_requests.begin();
i != copied_requests.end(); ++i) {
i->first.provider->CancelRequest(i->first.handle);
}
copied_requests.clear();
// That should have cleared all the pending items.
DCHECK(pending_requests_.empty());
}
template<class T>
void CancelableRequestConsumerTSimple<T>::CancelAllRequestsForClientData(
T client_data) {
PendingRequestList copied_requests(pending_requests_);
for (typename PendingRequestList::const_iterator i = copied_requests.begin();
i != copied_requests.end(); ++i) {
if (i->second == client_data)
i->first.provider->CancelRequest(i->first.handle);
}
copied_requests.clear();
}
template<class T>
bool CancelableRequestConsumerTSimple<T>::GetFirstHandleForClientData(
T client_data,
CancelableRequestProvider::Handle* handle) {
for (typename PendingRequestList::const_iterator i =
pending_requests_.begin(); i != pending_requests_.end(); ++i) {
if (i->second == client_data) {
*handle = i->first.handle;
return true;
}
}
*handle = 0;
return false;
}
template<class T>
void CancelableRequestConsumerTSimple<T>::GetAllClientData(
std::vector<T>* data) {
DCHECK(data);
for (typename PendingRequestList::iterator i = pending_requests_.begin();
i != pending_requests_.end(); ++i)
data->push_back(i->second);
}
template<class T>
T CancelableRequestConsumerTSimple<T>::get_initial_t() const {
return T();
}
template<class T>
void CancelableRequestConsumerTSimple<T>::OnRequestAdded(
CancelableRequestProvider* provider,
CancelableRequestProvider::Handle handle) {
// Make sure we're not mixing/matching providers (since the provider is
// responsible for providing thread safety until http://crbug.com/85970 is
// fixed, we can't use the same consumer with multiple providers).
#ifndef NDEBUG
if (!pending_requests_.empty())
DCHECK(pending_requests_.begin()->first.provider == provider);
#endif
DCHECK(pending_requests_.find(PendingRequest(provider, handle)) ==
pending_requests_.end());
pending_requests_[PendingRequest(provider, handle)] = get_initial_t();
}
template<class T>
void CancelableRequestConsumerTSimple<T>::OnRequestRemoved(
CancelableRequestProvider* provider,
CancelableRequestProvider::Handle handle) {
typename PendingRequestList::iterator i =
pending_requests_.find(PendingRequest(provider, handle));
if (i == pending_requests_.end()) {
NOTREACHED() << "Got a complete notification for a nonexistent request";
return;
}
pending_requests_.erase(i);
}
template<class T>
void CancelableRequestConsumerTSimple<T>::WillExecute(
CancelableRequestProvider* provider,
CancelableRequestProvider::Handle handle) {
current_request_ = PendingRequest(provider, handle);
}
template<class T>
void CancelableRequestConsumerTSimple<T>::DidExecute(
CancelableRequestProvider* provider,
CancelableRequestProvider::Handle handle) {
current_request_ = PendingRequest();
}
// See CancelableRequestConsumerTSimple. The default value for T
// is given in |initial_t|.
template<class T, T initial_t>
class CancelableRequestConsumerT
: public CancelableRequestConsumerTSimple<T> {
public:
CancelableRequestConsumerT();
virtual ~CancelableRequestConsumerT();
protected:
virtual T get_initial_t() const;
};
template<class T, T initial_t>
CancelableRequestConsumerT<T, initial_t>::CancelableRequestConsumerT() {
}
template<class T, T initial_t>
CancelableRequestConsumerT<T, initial_t>::~CancelableRequestConsumerT() {
}
template<class T, T initial_t>
T CancelableRequestConsumerT<T, initial_t>::get_initial_t() const {
return initial_t;
}
// Some clients may not want to store data. Rather than do some complicated
// thing with virtual functions to allow some consumers to store extra data and
// some not to, we just define a default one that stores some dummy data.
typedef CancelableRequestConsumerT<int, 0> CancelableRequestConsumer;
// MSVC doesn't like complex extern templates and DLLs.
#if !defined(COMPILER_MSVC)
// The vast majority of CancelableRequestConsumers are instantiated on <int>,
// so prevent that template from being expanded in normal code.
extern template class CancelableRequestConsumerTSimple<int>;
// We'll also want to extern-template the most common, typedef-ed
// CancelableRequestConsumerT.
extern template class CancelableRequestConsumerT<int, 0>;
#endif
// CancelableRequest ----------------------------------------------------------
//
// The request object that is used by a CancelableRequestProvider to send
// results to a CancelableRequestConsumer. This request handles the returning
// of results from a thread where the request is being executed to the thread
// and callback where the results are used. IT SHOULD BE PASSED AS A
// scoped_refptr TO KEEP IT ALIVE.
//
// It does not handle input parameters to the request. The caller must either
// transfer those separately or derive from this class to add the desired
// parameters.
//
// When the processing is complete on this message, the caller MUST call
// ForwardResult() with the return arguments that will be passed to the
// callback. If the request has been canceled, Return is optional (it will not
// do anything). If you do not have to return to the caller, the cancelable
// request system should not be used! (just use regular fire-and-forget tasks).
//
// Callback parameters are passed by value. In some cases, the request will
// want to return a large amount of data (for example, an image). One good
// approach is to derive from the CancelableRequest and make the data object
// (for example, a std::vector) owned by the CancelableRequest. The pointer
// to this data would be passed for the callback parameter. Since the
// CancelableRequest outlives the callback call, the data will be valid on the
// other thread for the callback, but will still be destroyed properly.
// Non-templatized base class that provides cancellation
class CancelableRequestBase
: public base::RefCountedThreadSafe<CancelableRequestBase> {
public:
friend class CancelableRequestProvider;
// Initializes most things to empty, Init() must be called to complete
// initialization of the object. This will be done by the provider when the
// request is dispatched.
//
// This must be called on the same thread the callback will be executed on, it
// will save that thread for later.
//
// This two-phase init is done so that the constructor can have no parameters,
// which makes it much more convenient for derived classes, which can be
// common. The derived classes need only declare the variables they provide in
// the constructor rather than many lines of internal tracking data that are
// passed to the base class (us).
//
// In addition, not all of the information (for example, the handle) is known
// at construction time.
CancelableRequestBase();
CancelableRequestConsumerBase* consumer() const {
return consumer_;
}
CancelableRequestProvider::Handle handle() const {
return handle_;
}
// The canceled flag indicates that the request should not be executed.
// A request can never be uncanceled, so only a setter for true is provided.
// This can be called multiple times, but only from one thread.
void set_canceled() {
canceled_.Set();
}
bool canceled() {
return canceled_.IsSet();
}
protected:
friend class base::RefCountedThreadSafe<CancelableRequestBase>;
virtual ~CancelableRequestBase();
// Initializes the object with the particulars from the provider. It may only
// be called once (it is called by the provider, which is a friend).
void Init(CancelableRequestProvider* provider,
CancelableRequestProvider::Handle handle,
CancelableRequestConsumerBase* consumer);
// Attempts to execute callback on |callback_thread_| if the request has not
// been canceled yet.
void DoForward(const base::Closure& forwarded_call, bool force_async);
// Tells the provider that the request is complete, which then tells the
// consumer.
void NotifyCompleted() const {
provider_->RequestCompleted(handle());
consumer_->DidExecute(provider_, handle_);
}
// Cover method for CancelableRequestConsumerBase::WillExecute.
void WillExecute() {
consumer_->WillExecute(provider_, handle_);
}
// The message loop that this request was created on. The callback will
// happen on the same thread.
MessageLoop* callback_thread_;
// The provider for this request. When we execute, we will notify this that
// request is complete to it can remove us from the requests it tracks.
CancelableRequestProvider* provider_;
// Notified after we execute that the request is complete. This should only
// be accessed if !canceled_.IsSet(), otherwise the pointer is invalid.
CancelableRequestConsumerBase* consumer_;
// The handle to this request inside the provider. This will be initialized
// to 0 when the request is created, and the provider will set it once the
// request has been dispatched.
CancelableRequestProvider::Handle handle_;
// Set if the caller cancels this request. No callbacks should be made when
// this is set.
base::CancellationFlag canceled_;
private:
// Executes the |forwarded_call| and notifies the provider and the consumer
// that this request has been completed. This must be called on the
// |callback_thread_|.
void ExecuteCallback(const base::Closure& forwarded_call);
DISALLOW_COPY_AND_ASSIGN(CancelableRequestBase);
};
// Templatized class. This is the one you should use directly or inherit from.
// The callback can be invoked by calling the ForwardResult() method. For this,
// you must either pack the parameters into a tuple, or use DispatchToMethod
// (in tuple.h).
//
// If you inherit to add additional input parameters or to do more complex
// memory management (see the bigger comment about this above), you can put
// those on a subclass of this.
//
// We have decided to allow users to treat derived classes of this as structs,
// so you can add members without getters and setters (which just makes the
// code harder to read). Don't use underscores after these vars. For example:
//
// typedef Callback1<int>::Type DoodieCallback;
//
// class DoodieRequest : public CancelableRequest<DoodieCallback> {
// public:
// DoodieRequest(CallbackType* callback) : CancelableRequest(callback) {
// }
//
// private:
// ~DoodieRequest() {}
//
// int input_arg1;
// std::wstring input_arg2;
// };
template<typename CB>
class CancelableRequest : public CancelableRequestBase {
public:
// TODO(ajwong): After all calls have been migrated, remove this template in
// favor of the specialization on base::Callback<Sig>.
typedef CB CallbackType; // CallbackRunner<...>
typedef typename CB::TupleType TupleType; // Tuple of the callback args.
// The provider MUST call Init() (on the base class) before this is valid.
// This class will take ownership of the callback object and destroy it when
// appropriate.
explicit CancelableRequest(CallbackType* callback)
: CancelableRequestBase(),
callback_(callback) {
DCHECK(callback) << "We should always have a callback";
}
// Dispatches the parameters to the correct thread so the callback can be
// executed there. The caller does not need to check for cancel before
// calling this. It is optional in the cancelled case. In the non-cancelled
// case, this MUST be called.
//
// If there are any pointers in the parameters, they must live at least as
// long as the request so that it can be forwarded to the other thread.
// For complex objects, this would typically be done by having a derived
// request own the data itself.
void ForwardResult(const TupleType& param) {
DCHECK(callback_.get());
if (!canceled()) {
if (callback_thread_ == MessageLoop::current()) {
// We can do synchronous callbacks when we're on the same thread.
ExecuteCallback(param);
} else {
callback_thread_->PostTask(
FROM_HERE,
base::Bind(&CancelableRequest<CB>::ExecuteCallback, this, param));
}
}
}
// Like |ForwardResult| but this never does a synchronous callback.
void ForwardResultAsync(const TupleType& param) {
DCHECK(callback_.get());
if (!canceled()) {
callback_thread_->PostTask(
FROM_HERE,
base::Bind(&CancelableRequest<CB>::ExecuteCallback, this, param));
}
}
protected:
virtual ~CancelableRequest() {}
private:
// Executes the callback and notifies the provider and the consumer that this
// request has been completed. This must be called on the callback_thread_.
void ExecuteCallback(const TupleType& param) {
if (!canceled_.IsSet()) {
WillExecute();
// Execute the callback.
callback_->RunWithParams(param);
}
// Notify the provider that the request is complete. The provider will
// notify the consumer for us. Note that it is possible for the callback to
// cancel this request; we must check canceled again.
if (!canceled_.IsSet())
NotifyCompleted();
}
// This should only be executed if !canceled_.IsSet(),
// otherwise the pointers may be invalid.
scoped_ptr<CallbackType> callback_;
};
// CancelableRequest<> wraps a normal base::Callback<> for use in the
// CancelableRequest framework.
//
// When using this class, the provider MUST call Init() (on the base class)
// before this is valid.
//
// The two functions ForwardResult(), and ForwardResultAsync() are used to
// invoke the wrapped callback on the correct thread. They are the same
// except that ForwardResult() will run the callback synchronously if
// we are already on the right thread.
//
// The caller does not need to check for cancel before calling ForwardResult()
// or ForwardResultAsync(). If the request has not been canceled, one of the
// these MUST be called.
//
// If there are any pointers in the parameters, they must live at least as
// long as the request so that it can be forwarded to the other thread.
// For complex objects, this would typically be done by having a derived
// request own the data itself.
//
// The following specializations handle different arities of base::Callbacks<>.
template<>
class CancelableRequest<base::Closure> : public CancelableRequestBase {
public:
typedef base::Closure CallbackType;
explicit CancelableRequest(const CallbackType& callback)
: CancelableRequestBase(),
callback_(callback) {
DCHECK(!callback.is_null()) << "Callback must be initialized.";
}
void ForwardResult(void) {
if (canceled()) return;
DoForward(callback_, false);
}
void ForwardResultAsync() {
if (canceled()) return;
DoForward(callback_, true);
}
protected:
virtual ~CancelableRequest() {}
private:
CallbackType callback_;
};
template<typename A1>
class CancelableRequest<base::Callback<void(A1)> >
: public CancelableRequestBase {
public:
typedef base::Callback<void(A1)> CallbackType;
explicit CancelableRequest(const CallbackType& callback)
: CancelableRequestBase(),
callback_(callback) {
DCHECK(!callback.is_null()) << "Callback must be initialized.";
}
void ForwardResult(
typename base::internal::CallbackParamTraits<A1>::ForwardType a1) {
if (canceled()) return;
DoForward(base::Bind(callback_, a1), false);
}
void ForwardResultAsync(
typename base::internal::CallbackParamTraits<A1>::ForwardType a1) {
if (canceled()) return;
DoForward(base::Bind(callback_, a1), true);
}
protected:
virtual ~CancelableRequest() {}
private:
CallbackType callback_;
};
template<typename A1, typename A2>
class CancelableRequest<base::Callback<void(A1,A2)> >
: public CancelableRequestBase {
public:
typedef base::Callback<void(A1,A2)> CallbackType;
explicit CancelableRequest(const CallbackType& callback)
: CancelableRequestBase(),
callback_(callback) {
DCHECK(!callback.is_null()) << "Callback must be initialized.";
}
void ForwardResult(
typename base::internal::CallbackParamTraits<A1>::ForwardType a1,
typename base::internal::CallbackParamTraits<A2>::ForwardType a2) {
if (canceled()) return;
DoForward(base::Bind(callback_, a1, a2), false);
}
void ForwardResultAsync(
typename base::internal::CallbackParamTraits<A1>::ForwardType a1,
typename base::internal::CallbackParamTraits<A2>::ForwardType a2) {
if (canceled()) return;
DoForward(base::Bind(callback_, a1, a2), true);
}
protected:
virtual ~CancelableRequest() {}
private:
CallbackType callback_;
};
template<typename A1, typename A2, typename A3>
class CancelableRequest<base::Callback<void(A1,A2,A3)> >
: public CancelableRequestBase {
public:
typedef base::Callback<void(A1,A2,A3)> CallbackType;
explicit CancelableRequest(const CallbackType& callback)
: CancelableRequestBase(),
callback_(callback) {
DCHECK(!callback.is_null()) << "Callback must be initialized.";
}
void ForwardResult(
typename base::internal::CallbackParamTraits<A1>::ForwardType a1,
typename base::internal::CallbackParamTraits<A2>::ForwardType a2,
typename base::internal::CallbackParamTraits<A3>::ForwardType a3) {
if (canceled()) return;
DoForward(base::Bind(callback_, a1, a2, a3), false);
}
void ForwardResultAsync(
typename base::internal::CallbackParamTraits<A1>::ForwardType a1,
typename base::internal::CallbackParamTraits<A2>::ForwardType a2,
typename base::internal::CallbackParamTraits<A3>::ForwardType a3) {
if (canceled()) return;
DoForward(base::Bind(callback_, a1, a2, a3), true);
}
protected:
virtual ~CancelableRequest() {}
private:
CallbackType callback_;
};
template<typename A1, typename A2, typename A3, typename A4>
class CancelableRequest<base::Callback<void(A1, A2, A3, A4)> >
: public CancelableRequestBase {
public:
typedef base::Callback<void(A1, A2, A3, A4)> CallbackType;
explicit CancelableRequest(const CallbackType& callback)
: CancelableRequestBase(),
callback_(callback) {
DCHECK(!callback.is_null()) << "Callback must be initialized.";
}
void ForwardResult(
typename base::internal::CallbackParamTraits<A1>::ForwardType a1,
typename base::internal::CallbackParamTraits<A2>::ForwardType a2,
typename base::internal::CallbackParamTraits<A3>::ForwardType a3,
typename base::internal::CallbackParamTraits<A4>::ForwardType a4) {
if (canceled()) return;
DoForward(base::Bind(callback_, a1, a2, a3, a4), false);
}
void ForwardResultAsync(
typename base::internal::CallbackParamTraits<A1>::ForwardType a1,
typename base::internal::CallbackParamTraits<A2>::ForwardType a2,
typename base::internal::CallbackParamTraits<A3>::ForwardType a3,
typename base::internal::CallbackParamTraits<A4>::ForwardType a4) {
if (canceled()) return;
DoForward(base::Bind(callback_, a1, a2, a3, a4), true);
}
protected:
virtual ~CancelableRequest() {}
private:
CallbackType callback_;
};
template<typename A1, typename A2, typename A3, typename A4, typename A5>
class CancelableRequest<base::Callback<void(A1, A2, A3, A4, A5)> >
: public CancelableRequestBase {
public:
typedef base::Callback<void(A1, A2, A3, A4, A5)> CallbackType;
explicit CancelableRequest(const CallbackType& callback)
: CancelableRequestBase(),
callback_(callback) {
DCHECK(!callback.is_null()) << "Callback must be initialized.";
}
void ForwardResult(
typename base::internal::CallbackParamTraits<A1>::ForwardType a1,
typename base::internal::CallbackParamTraits<A2>::ForwardType a2,
typename base::internal::CallbackParamTraits<A3>::ForwardType a3,
typename base::internal::CallbackParamTraits<A4>::ForwardType a4,
typename base::internal::CallbackParamTraits<A5>::ForwardType a5) {
if (canceled()) return;
DoForward(base::Bind(callback_, a1, a2, a3, a4, a5), false);
}
void ForwardResultAsync(
typename base::internal::CallbackParamTraits<A1>::ForwardType a1,
typename base::internal::CallbackParamTraits<A2>::ForwardType a2,
typename base::internal::CallbackParamTraits<A3>::ForwardType a3,
typename base::internal::CallbackParamTraits<A4>::ForwardType a4,
typename base::internal::CallbackParamTraits<A5>::ForwardType a5) {
if (canceled()) return;
DoForward(base::Bind(callback_, a1, a2, a3, a4, a5), true);
}
protected:
virtual ~CancelableRequest() {}
private:
CallbackType callback_;
};
template<typename A1, typename A2, typename A3, typename A4, typename A5,
typename A6>
class CancelableRequest<base::Callback<void(A1, A2, A3, A4, A5, A6)> >
: public CancelableRequestBase {
public:
typedef base::Callback<void(A1, A2, A3, A4, A5, A6)> CallbackType;
explicit CancelableRequest(const CallbackType& callback)
: CancelableRequestBase(),
callback_(callback) {
DCHECK(!callback.is_null()) << "Callback must be initialized.";
}
void ForwardResult(
typename base::internal::CallbackParamTraits<A1>::ForwardType a1,
typename base::internal::CallbackParamTraits<A2>::ForwardType a2,
typename base::internal::CallbackParamTraits<A3>::ForwardType a3,
typename base::internal::CallbackParamTraits<A4>::ForwardType a4,
typename base::internal::CallbackParamTraits<A5>::ForwardType a5,
typename base::internal::CallbackParamTraits<A6>::ForwardType a6) {
if (canceled()) return;
DoForward(base::Bind(callback_, a1, a2, a3, a4, a5, a6), false);
}
void ForwardResultAsync(
typename base::internal::CallbackParamTraits<A1>::ForwardType a1,
typename base::internal::CallbackParamTraits<A2>::ForwardType a2,
typename base::internal::CallbackParamTraits<A3>::ForwardType a3,
typename base::internal::CallbackParamTraits<A4>::ForwardType a4,
typename base::internal::CallbackParamTraits<A5>::ForwardType a5,
typename base::internal::CallbackParamTraits<A6>::ForwardType a6) {
if (canceled()) return;
DoForward(base::Bind(callback_, a1, a2, a3, a4, a5, a6), true);
}
protected:
virtual ~CancelableRequest() {}
private:
CallbackType callback_;
};
// A CancelableRequest with a single value. This is intended for use when
// the provider provides a single value. The provider fills the result into
// the value, and notifies the request with a pointer to the value. For example,
// HistoryService has many methods that callback with a vector. Use the
// following pattern for this:
// 1. Define the callback:
// typedef Callback2<Handle, std::vector<Foo>*>::Type FooCallback;
// 2. Define the CancelableRequest1 type.
// typedef CancelableRequest1<FooCallback, std::vector<Foo>> FooRequest;
// 3. The provider method should then fill in the contents of the vector,
// forwarding the result like so:
// request->ForwardResult(FooRequest::TupleType(request->handle(),
// &request->value));
//
// Tip: for passing more than one value, use a Tuple for the value.
template<typename CB, typename Type>
class CancelableRequest1 : public CancelableRequest<CB> {
public:
explicit CancelableRequest1(
const typename CancelableRequest<CB>::CallbackType& callback)
: CancelableRequest<CB>(callback), value() {
}
// The value.
Type value;
protected:
virtual ~CancelableRequest1() {}
};
#endif // CHROME_BROWSER_COMMON_CANCELABLE_REQUEST_H_
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