blob: a5682a0585975012f853843eb718fbf7fb9942b0 [file] [log] [blame]
// 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.
// This file declares HttpCache::Transaction, a private class of HttpCache so
// it should only be included by
#include <stddef.h>
#include <stdint.h>
#include <memory>
#include <string>
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/time/time.h"
#include "net/base/completion_callback.h"
#include "net/base/completion_once_callback.h"
#include "net/base/completion_repeating_callback.h"
#include "net/base/io_buffer.h"
#include "net/base/ip_endpoint.h"
#include "net/base/load_states.h"
#include "net/base/net_error_details.h"
#include "net/base/request_priority.h"
#include "net/http/http_cache.h"
#include "net/http/http_request_headers.h"
#include "net/http/http_response_headers.h"
#include "net/http/http_response_info.h"
#include "net/http/http_transaction.h"
#include "net/http/partial_data.h"
#include "net/log/net_log_with_source.h"
#include "net/socket/connection_attempts.h"
#include "net/websockets/websocket_handshake_stream_base.h"
namespace net {
class PartialData;
struct HttpRequestInfo;
struct LoadTimingInfo;
class SSLPrivateKey;
// This is the transaction that is returned by the HttpCache transaction
// factory.
class NET_EXPORT_PRIVATE HttpCache::Transaction : public HttpTransaction {
// The transaction has the following modes, which apply to how it may access
// its cache entry.
// o If the mode of the transaction is NONE, then it is in "pass through"
// mode and all methods just forward to the inner network transaction.
// o If the mode of the transaction is only READ, then it may only read from
// the cache entry.
// o If the mode of the transaction is only WRITE, then it may only write to
// the cache entry.
// o If the mode of the transaction is READ_WRITE, then the transaction may
// optionally modify the cache entry (e.g., possibly corresponding to
// cache validation).
// o If the mode of the transaction is UPDATE, then the transaction may
// update existing cache entries, but will never create a new entry or
// respond using the entry read from the cache.
enum Mode {
NONE = 0,
READ_META = 1 << 0,
READ_DATA = 1 << 1,
WRITE = 1 << 2,
Transaction(RequestPriority priority,
HttpCache* cache);
~Transaction() override;
// Virtual so it can be extended for testing.
virtual Mode mode() const;
std::string& method() { return method_; }
const std::string& key() const { return cache_key_; }
// Writes |buf_len| bytes of meta-data from the provided buffer |buf|. to the
// HTTP cache entry that backs this transaction (if any).
// Returns the number of bytes actually written, or a net error code. If the
// operation cannot complete immediately, returns ERR_IO_PENDING, grabs a
// reference to the buffer (until completion), and notifies the caller using
// the provided |callback| when the operation finishes.
// The first time this method is called for a given transaction, previous
// meta-data will be overwritten with the provided data, and subsequent
// invocations will keep appending to the cached entry.
// In order to guarantee that the metadata is set to the correct entry, the
// response (or response info) must be evaluated by the caller, for instance
// to make sure that the response_time is as expected, before calling this
// method.
int WriteMetadata(IOBuffer* buf,
int buf_len,
const CompletionCallback& callback);
HttpCache::ActiveEntry* entry() { return entry_; }
// Returns the LoadState of the writer transaction of a given ActiveEntry. In
// other words, returns the LoadState of this transaction without asking the
// http cache, because this transaction should be the one currently writing
// to the cache entry.
LoadState GetWriterLoadState() const;
const CompletionCallback& io_callback() { return io_callback_; }
const NetLogWithSource& net_log() const;
// Bypasses the cache lock whenever there is lock contention.
void BypassLockForTest() {
bypass_lock_for_test_ = true;
void BypassLockAfterHeadersForTest() {
bypass_lock_after_headers_for_test_ = true;
// Generates a failure when attempting to conditionalize a network request.
void FailConditionalizationForTest() {
fail_conditionalization_for_test_ = true;
// HttpTransaction methods:
int Start(const HttpRequestInfo* request_info,
CompletionOnceCallback callback,
const NetLogWithSource& net_log) override;
int RestartIgnoringLastError(CompletionOnceCallback callback) override;
int RestartWithCertificate(scoped_refptr<X509Certificate> client_cert,
scoped_refptr<SSLPrivateKey> client_private_key,
CompletionOnceCallback callback) override;
int RestartWithAuth(const AuthCredentials& credentials,
CompletionOnceCallback callback) override;
bool IsReadyToRestartForAuth() override;
int Read(IOBuffer* buf,
int buf_len,
CompletionOnceCallback callback) override;
void StopCaching() override;
bool GetFullRequestHeaders(HttpRequestHeaders* headers) const override;
int64_t GetTotalReceivedBytes() const override;
int64_t GetTotalSentBytes() const override;
void DoneReading() override;
const HttpResponseInfo* GetResponseInfo() const override;
LoadState GetLoadState() const override;
void SetQuicServerInfo(QuicServerInfo* quic_server_info) override;
bool GetLoadTimingInfo(LoadTimingInfo* load_timing_info) const override;
bool GetRemoteEndpoint(IPEndPoint* endpoint) const override;
void PopulateNetErrorDetails(NetErrorDetails* details) const override;
void SetPriority(RequestPriority priority) override;
void SetWebSocketHandshakeStreamCreateHelper(
WebSocketHandshakeStreamBase::CreateHelper* create_helper) override;
void SetBeforeNetworkStartCallback(
const BeforeNetworkStartCallback& callback) override;
void SetBeforeHeadersSentCallback(
const BeforeHeadersSentCallback& callback) override;
void SetRequestHeadersCallback(RequestHeadersCallback callback) override;
void SetResponseHeadersCallback(ResponseHeadersCallback callback) override;
int ResumeNetworkStart() override;
void GetConnectionAttempts(ConnectionAttempts* out) const override;
// Invoked when parallel validation cannot proceed due to response failure
// and this transaction needs to be restarted.
void SetValidatingCannotProceed();
// Invoked to remove the association between a transaction waiting to be
// added to an entry and the entry.
void ResetCachePendingState() { cache_pending_ = false; }
// Returns the estimate of dynamically allocated memory in bytes.
size_t EstimateMemoryUsage() const;
RequestPriority priority() const { return priority_; }
PartialData* partial() { return partial_.get(); }
bool is_truncated() { return truncated_; }
// Invoked when this writer transaction is about to be removed from entry.
// If result is an error code, a future Read should fail with |result|.
void WriterAboutToBeRemovedFromEntry(int result);
// Invoked when this transaction is about to become a reader because the cache
// entry has finished writing.
void WriteModeTransactionAboutToBecomeReader();
// Invoked when HttpCache decides whether this transaction should join
// parallel writing or create a new writers object. This is then used
// for logging metrics. Can be called repeatedly, but doesn't change once the
// value has been set to something other than PARALLEL_WRITING_NONE.
void MaybeSetParallelWritingPatternForMetrics(ParallelWritingPattern pattern);
static const size_t kNumValidationHeaders = 2;
// Helper struct to pair a header name with its value, for
// headers used to validate cache entries.
struct ValidationHeaders {
ValidationHeaders() : initialized(false) {}
std::string values[kNumValidationHeaders];
void Reset() {
initialized = false;
for (auto& value : values)
bool initialized;
struct NetworkTransactionInfo {
// Load timing information for the last network request, if any. Set in the
// 304 and 206 response cases, as the network transaction may be destroyed
// before the caller requests load timing information.
std::unique_ptr<LoadTimingInfo> old_network_trans_load_timing;
int64_t total_received_bytes = 0;
int64_t total_sent_bytes = 0;
ConnectionAttempts old_connection_attempts;
IPEndPoint old_remote_endpoint;
HttpRequestHeaders full_request_headers;
enum State {
// Normally, states are traversed in approximately this order.
// These states are entered from Read.
// These states are entered if the request should be handled exclusively
// by the network layer (skipping the cache entirely).
// Used for categorizing validation triggers in histograms.
// NOTE: This enumeration is used in histograms, so please do not add entries
// in the middle.
enum ValidationCause {
enum MemoryEntryDataHints {
// If this hint is set, the caching headers indicate we can't do anything
// with this entry (unless we are ignoring them thanks to a loadflag),
// i.e. it's expired and has nothing that permits validations.
// Runs the state transition loop. Resets and calls |callback_| on exit,
// unless the return value is ERR_IO_PENDING.
int DoLoop(int result);
// Each of these methods corresponds to a State value. If there is an
// argument, the value corresponds to the return of the previous state or
// corresponding callback.
int DoGetBackend();
int DoGetBackendComplete(int result);
int DoInitEntry();
int DoOpenEntry();
int DoOpenEntryComplete(int result);
int DoDoomEntry();
int DoDoomEntryComplete(int result);
int DoCreateEntry();
int DoCreateEntryComplete(int result);
int DoAddToEntry();
int DoAddToEntryComplete(int result);
int DoDoneHeadersAddToEntryComplete(int result);
int DoCacheReadResponse();
int DoCacheReadResponseComplete(int result);
int DoCacheToggleUnusedSincePrefetch();
int DoCacheToggleUnusedSincePrefetchComplete(int result);
int DoCacheDispatchValidation();
int DoCacheQueryData();
int DoCacheQueryDataComplete(int result);
int DoCacheUpdateStaleWhileRevalidateTimeout();
int DoCacheUpdateStaleWhileRevalidateTimeoutComplete(int result);
int DoSetupEntryForRead();
int DoStartPartialCacheValidation();
int DoCompletePartialCacheValidation(int result);
int DoSendRequest();
int DoSendRequestComplete(int result);
int DoSuccessfulSendRequest();
int DoUpdateCachedResponse();
int DoCacheWriteUpdatedResponse();
int DoCacheWriteUpdatedResponseComplete(int result);
int DoUpdateCachedResponseComplete(int result);
int DoOverwriteCachedResponse();
int DoCacheWriteResponse();
int DoCacheWriteResponseComplete(int result);
int DoTruncateCachedData();
int DoTruncateCachedDataComplete(int result);
int DoTruncateCachedMetadata();
int DoTruncateCachedMetadataComplete(int result);
int DoPartialHeadersReceived();
int DoCacheReadMetadata();
int DoCacheReadMetadataComplete(int result);
int DoHeadersPhaseCannotProceed(int result);
int DoFinishHeaders(int result);
int DoFinishHeadersComplete(int result);
int DoNetworkReadCacheWrite();
int DoNetworkReadCacheWriteComplete(int result);
int DoCacheReadData();
int DoCacheReadDataComplete(int result);
int DoNetworkRead();
int DoNetworkReadComplete(int result);
// Adds time out handling while waiting to be added to entry or after headers
// phase is complete.
void AddCacheLockTimeoutHandler(ActiveEntry* entry);
// Sets request_ and fields derived from it.
void SetRequest(const NetLogWithSource& net_log);
// Returns true if the request should be handled exclusively by the network
// layer (skipping the cache entirely).
bool ShouldPassThrough();
// Called to begin reading from the cache. Returns network error code.
int BeginCacheRead();
// Called to begin validating the cache entry. Returns network error code.
int BeginCacheValidation();
// Called to begin validating an entry that stores partial content. Returns
// a network error code.
int BeginPartialCacheValidation();
// Validates the entry headers against the requested range and continues with
// the validation of the rest of the entry. Returns a network error code.
int ValidateEntryHeadersAndContinue();
// Called to start requests which were given an "if-modified-since" or
// "if-none-match" validation header by the caller (NOT when the request was
// conditionalized internally in response to LOAD_VALIDATE_CACHE).
// Returns a network error code.
int BeginExternallyConditionalizedRequest();
// Called to restart a network transaction after an error. Returns network
// error code.
int RestartNetworkRequest();
// Called to restart a network transaction with a client certificate.
// Returns network error code.
int RestartNetworkRequestWithCertificate(
scoped_refptr<X509Certificate> client_cert,
scoped_refptr<SSLPrivateKey> client_private_key);
// Called to restart a network transaction with authentication credentials.
// Returns network error code.
int RestartNetworkRequestWithAuth(const AuthCredentials& credentials);
// Called to determine if we need to validate the cache entry before using it,
// and whether the validation should be synchronous or asynchronous.
ValidationType RequiresValidation();
// Called to make the request conditional (to ask the server if the cached
// copy is valid). Returns true if able to make the request conditional.
bool ConditionalizeRequest();
// Determines if saved response permits conditionalization, and extracts
// etag/last-modified values. Only depends on |response_.headers|.
// |*etag_value| and |*last_modified_value| will be set if true is returned,
// but may also be modified in other cases.
bool IsResponseConditionalizable(std::string* etag_value,
std::string* last_modified_value) const;
// Returns true if the resource info MemoryEntryDataHints bit flags in
// |in_memory_info| and the current request & load flags suggest that
// the cache entry in question is not actually usable for HTTP
// (i.e. already expired, and nothing is forcing us to disregard that).
bool MaybeRejectBasedOnEntryInMemoryData(uint8_t in_memory_info);
// Returns true if response_ is such that, if saved to cache, it would only
// be usable if load flags asked us to ignore caching headers.
// (return value of false makes no statement as to suitability of the entry).
bool ComputeUnusablePerCachingHeaders();
// Makes sure that a 206 response is expected. Returns true on success.
// On success, handling_206_ will be set to true if we are processing a
// partial entry.
bool ValidatePartialResponse();
// Handles a response validation error by bypassing the cache.
void IgnoreRangeRequest();
// Fixes the response headers to match expectations for a HEAD request.
void FixHeadersForHead();
// Called to write data to the cache entry. If the write fails, then the
// cache entry is destroyed. Future calls to this function will just do
// nothing without side-effect. Returns a network error code.
int WriteToEntry(int index, int offset, IOBuffer* data, int data_len,
const CompletionCallback& callback);
// Called to write response_ to the cache entry. |truncated| indicates if the
// entry should be marked as incomplete.
int WriteResponseInfoToEntry(bool truncated);
// Helper function, should be called with result of WriteResponseInfoToEntry
// (or the result of the callback, when WriteResponseInfoToEntry returns
// ERR_IO_PENDING). Calls DoneWithEntry if |result| is not the right
// number of bytes. It is expected that the state that calls this will
// return whatever net error code this function returns, which currently
// is always "OK".
int OnWriteResponseInfoToEntryComplete(int result);
// Configures the transaction to read from the network and stop writing to the
// entry. It will release the entry if possible. Returns true if caching could
// be stopped successfully. It will not be stopped if there are multiple
// transactions writing to the cache simultaneously.
bool StopCachingImpl(bool success);
// Informs the HttpCache that this transaction is done with the entry and
// changes the mode to NONE. Set |entry_is_complete| to false if the
// transaction has not yet finished fully writing or reading the request
// to/from the entry. If |entry_is_complete| is false the result may be either
// a truncated or a doomed entry based on whether the stored response can be
// resumed or not.
void DoneWithEntry(bool did_finish);
// Returns an error to signal the caller that the current read failed. The
// current operation |result| is also logged. If |restart| is true, the
// transaction should be restarted.
int OnCacheReadError(int result, bool restart);
// Called when the cache lock timeout fires.
void OnCacheLockTimeout(base::TimeTicks start_time);
// Deletes the current partial cache entry (sparse), and optionally removes
// the control object (partial_).
void DoomPartialEntry(bool delete_object);
// Performs the needed work after receiving data from the network, when
// working with range requests.
int DoPartialNetworkReadCompleted(int result);
// Performs the needed work after receiving data from the cache, when
// working with range requests.
int DoPartialCacheReadCompleted(int result);
// Restarts this transaction after deleting the cached data. It is meant to
// be used when the current request cannot be fulfilled due to conflicts
// between the byte range request and the cached entry.
int DoRestartPartialRequest();
// Resets the relavant internal state to remove traces of internal processing
// related to range requests. Deletes |partial_| if |delete_object| is true.
void ResetPartialState(bool delete_object);
// Resets |network_trans_|, which must be non-NULL. Also updates
// |old_network_trans_load_timing_|, which must be NULL when this is called.
void ResetNetworkTransaction();
// Returns the currently active network transaction.
const HttpTransaction* network_transaction() const;
HttpTransaction* network_transaction();
// Returns the network transaction from |this| or from writers only if it was
// moved from |this| to writers. This is so that statistics of the network
// transaction are not attributed to any other writer member.
const HttpTransaction* GetOwnedOrMovedNetworkTransaction() const;
// Returns true if we should bother attempting to resume this request if it is
// aborted while in progress. If |has_data| is true, the size of the stored
// data is considered for the result.
bool CanResume(bool has_data);
// Setter for response_ and auth_response_. It updates its cache entry status,
// if needed.
void SetResponse(const HttpResponseInfo& new_response);
void SetAuthResponse(const HttpResponseInfo& new_response);
void UpdateCacheEntryStatus(
HttpResponseInfo::CacheEntryStatus new_cache_entry_status);
// Sets the response.cache_entry_status to the current cache_entry_status_.
void SyncCacheEntryStatusToResponse();
// Logs histograms for this transaction. It is invoked when the transaction is
// either complete or is done writing to entry and will continue in
// network-only mode.
void RecordHistograms();
// Returns true if this transaction is a member of entry_->writers.
bool InWriters() const;
// Called to signal completion of asynchronous IO. Note that this callback is
// used in the conventional sense where one layer calls the callback of the
// layer above it e.g. this callback gets called from the network transaction
// layer. In addition, it is also used for HttpCache layer to let this
// transaction know when it is out of a queued state in ActiveEntry and can
// continue its processing.
void OnIOComplete(int result);
// When in a DoLoop, use this to set the next state as it verifies that the
// state isn't set twice.
void TransitionToState(State state);
// Helper function to decide the next reading state.
int TransitionToReadingState();
// Saves network transaction info using |transaction|.
void SaveNetworkTransactionInfo(const HttpTransaction& transaction);
State next_state_;
// Initial request with which Start() was invoked.
const HttpRequestInfo* initial_request_;
const HttpRequestInfo* request_;
std::string method_;
RequestPriority priority_;
NetLogWithSource net_log_;
std::unique_ptr<HttpRequestInfo> custom_request_;
HttpRequestHeaders request_headers_copy_;
// If extra_headers specified a "if-modified-since" or "if-none-match",
// |external_validation_| contains the value of those headers.
ValidationHeaders external_validation_;
base::WeakPtr<HttpCache> cache_;
HttpCache::ActiveEntry* entry_;
HttpCache::ActiveEntry* new_entry_;
std::unique_ptr<HttpTransaction> network_trans_;
CompletionOnceCallback callback_; // Consumer's callback.
HttpResponseInfo response_;
HttpResponseInfo auth_response_;
const HttpResponseInfo* new_response_;
std::string cache_key_;
Mode mode_;
bool reading_; // We are already reading. Never reverts to false once set.
bool invalid_range_; // We may bypass the cache for this request.
bool truncated_; // We don't have all the response data.
bool is_sparse_; // The data is stored in sparse byte ranges.
bool range_requested_; // The user requested a byte range.
bool handling_206_; // We must deal with this 206 response.
bool cache_pending_; // We are waiting for the HttpCache.
// Headers have been received from the network and it's not a match with the
// existing entry.
bool done_headers_create_new_entry_;
bool vary_mismatch_; // The request doesn't match the stored vary data.
bool couldnt_conditionalize_request_;
bool bypass_lock_for_test_; // A test is exercising the cache lock.
bool bypass_lock_after_headers_for_test_; // A test is exercising the cache
// lock.
bool fail_conditionalization_for_test_; // Fail ConditionalizeRequest.
scoped_refptr<IOBuffer> read_buf_;
int io_buf_len_;
int read_offset_;
int effective_load_flags_;
std::unique_ptr<PartialData> partial_; // We are dealing with range requests.
CompletionRepeatingCallback io_callback_;
// Error code to be returned from a subsequent Read call if shared writing
// failed in a separate transaction.
int shared_writing_error_;
// Members used to track data for histograms.
// This cache_entry_status_ takes precedence over
// response_.cache_entry_status. In fact, response_.cache_entry_status must be
// kept in sync with cache_entry_status_ (via SetResponse and
// UpdateCacheEntryStatus).
HttpResponseInfo::CacheEntryStatus cache_entry_status_;
ValidationCause validation_cause_;
base::TimeTicks entry_lock_waiting_since_;
base::TimeTicks first_cache_access_since_;
base::TimeTicks send_request_since_;
base::Time open_entry_last_used_;
base::TimeDelta stale_entry_freshness_;
base::TimeDelta stale_entry_age_;
bool cant_conditionalize_zero_freshness_from_memhint_;
bool recorded_histograms_;
ParallelWritingPattern parallel_writing_pattern_;
NetworkTransactionInfo network_transaction_info_;
// True if this transaction created the network transaction that is now being
// used by writers. This is used to check that only this transaction should
// account for the network bytes and other statistics of the network
// transaction.
// TODO(shivanisha) Note that if this transaction dies mid-way and there are
// other writer transactions, no transaction then accounts for those
// statistics.
bool moved_network_transaction_to_writers_;
// The helper object to use to create WebSocketHandshakeStreamBase
// objects. Only relevant when establishing a WebSocket connection.
// This is passed to the underlying network transaction. It is stored here in
// case the transaction does not exist yet.
BeforeNetworkStartCallback before_network_start_callback_;
BeforeHeadersSentCallback before_headers_sent_callback_;
RequestHeadersCallback request_headers_callback_;
ResponseHeadersCallback response_headers_callback_;
// True if the Transaction is currently processing the DoLoop.
bool in_do_loop_;
base::WeakPtrFactory<Transaction> weak_factory_;
} // namespace net