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net_instaweb::SyncFetcherAdapterCallback Class Reference

Class to help run an asynchronous fetch synchronously with a timeout. More...

#include "sync_fetcher_adapter_callback.h"

Inheritance diagram for net_instaweb::SyncFetcherAdapterCallback:
net_instaweb::AsyncFetch net_instaweb::Writer

Public Member Functions

 SyncFetcherAdapterCallback (ThreadSystem *thread_system, Writer *writer, const RequestContextPtr &request_context)
void Release () LOCKS_EXCLUDED(mutex_)
bool IsDone () const LOCKS_EXCLUDED(mutex_)
bool IsDoneLockHeld () const EXCLUSIVE_LOCKS_REQUIRED(mutex_)
 Version of IsDone() that may only be called if you already hold the mutex.
bool success () const LOCKS_EXCLUDED(mutex_)
bool released () const LOCKS_EXCLUDED(mutex_)
bool LockIfNotReleased () EXCLUSIVE_TRYLOCK_FUNCTION(true
void Unlock () UNLOCK_FUNCTION(mutex_)
 Releases mutex acquired by a successful LockIfNotReleased() call.
void TimedWait (int64 timeout_ms) EXCLUSIVE_LOCKS_REQUIRED(mutex_)
- Public Member Functions inherited from net_instaweb::AsyncFetch
 AsyncFetch (const RequestContextPtr &request_ctx)
void HeadersComplete ()
void Done (bool success)
virtual bool Write (const StringPiece &content, MessageHandler *handler)
virtual bool Flush (MessageHandler *handler)
virtual bool IsCachedResultValid (const ResponseHeaders &headers)
RequestHeadersrequest_headers ()
void set_request_headers (RequestHeaders *headers)
void SetRequestHeadersTakingOwnership (RequestHeaders *headers)
 Same as above, but takes ownership.
const RequestHeadersrequest_headers () const
ResponseHeadersresponse_headers ()
 See doc for request_headers and set_request_headers.
void set_response_headers (ResponseHeaders *headers)
ResponseHeadersextra_response_headers ()
void set_extra_response_headers (ResponseHeaders *headers)
virtual bool IsBackgroundFetch () const
virtual void Reset ()
bool headers_complete () const
bool content_length_known () const
int64 content_length () const
void set_content_length (int64 x)
GoogleString LoggingString ()
virtual const RequestContextPtrrequest_context ()
virtual AbstractLogRecordlog_record ()
void FixCacheControlForGoogleCache ()
- Public Member Functions inherited from net_instaweb::Writer
virtual bool Dump (Writer *writer, MessageHandler *message_handler)

Public Attributes

bool mutex_

Protected Member Functions

virtual void HandleDone (bool success) LOCKS_EXCLUDED(mutex_)
virtual bool HandleWrite (const StringPiece &content, MessageHandler *handler)
virtual bool HandleFlush (MessageHandler *handler)
virtual void HandleHeadersComplete ()

Additional Inherited Members

- Static Public Member Functions inherited from net_instaweb::AsyncFetch
static bool IsGoogleCacheVia (StringPiece via_value)
- Static Public Attributes inherited from net_instaweb::AsyncFetch
static const int kContentLengthUnknown = -1

Detailed Description

Class to help run an asynchronous fetch synchronously with a timeout.

Member Function Documentation

bool net_instaweb::SyncFetcherAdapterCallback::LockIfNotReleased ( )

If this fetcher hasn't yet been Released(), returns true with mutex_ held. Otherwise, returns false with the mutex_ released. These methods should be used to guard accesses to writer() and response_headers().

void net_instaweb::SyncFetcherAdapterCallback::Release ( )

When implementing a synchronous fetch with a timeout based on an underlying asynchronous mechanism, we need to ensure that we don't write to freed memory if the Done callback fires after the timeout.

So we need to make sure the Writer and Response Buffers are owned by this Callback class, which will forward the output and headers to the caller if it has not been released by the time the callback is called.

If this object may be accessed from multiple threads (e.g. due to async rewrites), you should use LockIfNotReleased() and Unlock() to guard access to these. When the 'owner' of this callback – the code that calls 'new' – is done with it, it can call Release(). That will arrange for the object to be deleted as soon as it's safe to do so, which may be immediately at the point of call, or from some asynchronous event. The object should not be used by the owner after Release() has been called.

void net_instaweb::SyncFetcherAdapterCallback::TimedWait ( int64  timeout_ms)

Waits on condition variable associated with the mutex, with timeout of timeout_ms. The wake up condition is Done() being called, but this merely waits for lookup and does not ensure the condition has occurred — the caller should use a while loop conditioned on done_lock_held(). Should not be called if this callback is already released, and expects mutex already held.

The documentation for this class was generated from the following file: