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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "net/http/http_cache.h" | 5 #include "net/http/http_cache.h" |
6 | 6 |
7 #include <algorithm> | 7 #include <algorithm> |
8 #include <utility> | 8 #include <utility> |
9 | 9 |
10 #include "base/bind.h" | 10 #include "base/bind.h" |
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89 true, | 89 true, |
90 thread_, | 90 thread_, |
91 net_log, | 91 net_log, |
92 backend, | 92 backend, |
93 callback); | 93 callback); |
94 } | 94 } |
95 | 95 |
96 //----------------------------------------------------------------------------- | 96 //----------------------------------------------------------------------------- |
97 | 97 |
98 HttpCache::ActiveEntry::ActiveEntry(disk_cache::Entry* entry) | 98 HttpCache::ActiveEntry::ActiveEntry(disk_cache::Entry* entry) |
99 : disk_entry(entry), | 99 : disk_entry(entry) {} |
100 writer(NULL), | |
101 will_process_pending_queue(false), | |
102 doomed(false) { | |
103 } | |
104 | 100 |
105 HttpCache::ActiveEntry::~ActiveEntry() { | 101 HttpCache::ActiveEntry::~ActiveEntry() { |
106 if (disk_entry) { | 102 if (disk_entry) { |
107 disk_entry->Close(); | 103 disk_entry->Close(); |
108 disk_entry = NULL; | 104 disk_entry = nullptr; |
109 } | 105 } |
110 } | 106 } |
111 | 107 |
112 size_t HttpCache::ActiveEntry::EstimateMemoryUsage() const { | 108 size_t HttpCache::ActiveEntry::EstimateMemoryUsage() const { |
113 // Skip |disk_entry| which is tracked in simple_backend_impl; Skip |readers| | 109 // Skip |disk_entry| which is tracked in simple_backend_impl; Skip |readers| |
114 // and |pending_queue| because the Transactions are owned by their respective | 110 // and |add_to_entry_queue| because the Transactions are owned by their |
115 // URLRequestHttpJobs. | 111 // respective URLRequestHttpJobs. |
116 return 0; | 112 return 0; |
117 } | 113 } |
118 | 114 |
119 bool HttpCache::ActiveEntry::HasNoTransactions() { | 115 bool HttpCache::ActiveEntry::HasNoTransactions() { |
120 return !writer && readers.empty() && pending_queue.empty(); | 116 return !writer && readers.empty() && add_to_entry_queue.empty() && |
117 done_headers_queue.empty() && !headers_transaction; | |
118 } | |
119 | |
120 bool HttpCache::ActiveEntry::HasNoActiveTransactions() { | |
121 return !writer && readers.empty() && !headers_transaction; | |
121 } | 122 } |
122 | 123 |
123 //----------------------------------------------------------------------------- | 124 //----------------------------------------------------------------------------- |
124 | 125 |
125 // This structure keeps track of work items that are attempting to create or | 126 // This structure keeps track of work items that are attempting to create or |
126 // open cache entries or the backend itself. | 127 // open cache entries or the backend itself. |
127 struct HttpCache::PendingOp { | 128 struct HttpCache::PendingOp { |
128 PendingOp() : disk_entry(NULL) {} | 129 PendingOp() : disk_entry(NULL) {} |
129 ~PendingOp() {} | 130 ~PendingOp() {} |
130 | 131 |
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353 } | 354 } |
354 } | 355 } |
355 } | 356 } |
356 | 357 |
357 HttpCache::~HttpCache() { | 358 HttpCache::~HttpCache() { |
358 // Transactions should see an invalid cache after this point; otherwise they | 359 // Transactions should see an invalid cache after this point; otherwise they |
359 // could see an inconsistent object (half destroyed). | 360 // could see an inconsistent object (half destroyed). |
360 weak_factory_.InvalidateWeakPtrs(); | 361 weak_factory_.InvalidateWeakPtrs(); |
361 | 362 |
362 // If we have any active entries remaining, then we need to deactivate them. | 363 // If we have any active entries remaining, then we need to deactivate them. |
363 // We may have some pending calls to OnProcessPendingQueue, but since those | 364 // We may have some pending tasks to process queued transactions ,but since |
364 // won't run (due to our destruction), we can simply ignore the corresponding | 365 // those won't run (due to our destruction), we can simply ignore the |
365 // will_process_pending_queue flag. | 366 // corresponding flags. |
366 while (!active_entries_.empty()) { | 367 while (!active_entries_.empty()) { |
367 ActiveEntry* entry = active_entries_.begin()->second.get(); | 368 ActiveEntry* entry = active_entries_.begin()->second.get(); |
368 entry->will_process_pending_queue = false; | 369 entry->will_process_queued_transactions = false; |
369 entry->pending_queue.clear(); | 370 entry->add_to_entry_queue.clear(); |
370 entry->readers.clear(); | 371 entry->readers.clear(); |
371 entry->writer = NULL; | 372 entry->done_headers_queue.clear(); |
373 entry->headers_transaction = nullptr; | |
374 entry->writer = nullptr; | |
372 DeactivateEntry(entry); | 375 DeactivateEntry(entry); |
373 } | 376 } |
374 | 377 |
375 doomed_entries_.clear(); | 378 doomed_entries_.clear(); |
376 | 379 |
377 // Before deleting pending_ops_, we have to make sure that the disk cache is | 380 // Before deleting pending_ops_, we have to make sure that the disk cache is |
378 // done with said operations, or it will attempt to use deleted data. | 381 // done with said operations, or it will attempt to use deleted data. |
379 disk_cache_.reset(); | 382 disk_cache_.reset(); |
380 | 383 |
381 for (auto pending_it = pending_ops_.begin(); pending_it != pending_ops_.end(); | 384 for (auto pending_it = pending_ops_.begin(); pending_it != pending_ops_.end(); |
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622 // We keep track of doomed entries so that we can ensure that they are | 625 // We keep track of doomed entries so that we can ensure that they are |
623 // cleaned up properly when the cache is destroyed. | 626 // cleaned up properly when the cache is destroyed. |
624 ActiveEntry* entry_ptr = entry.get(); | 627 ActiveEntry* entry_ptr = entry.get(); |
625 DCHECK_EQ(0u, doomed_entries_.count(entry_ptr)); | 628 DCHECK_EQ(0u, doomed_entries_.count(entry_ptr)); |
626 doomed_entries_[entry_ptr] = std::move(entry); | 629 doomed_entries_[entry_ptr] = std::move(entry); |
627 | 630 |
628 entry_ptr->disk_entry->Doom(); | 631 entry_ptr->disk_entry->Doom(); |
629 entry_ptr->doomed = true; | 632 entry_ptr->doomed = true; |
630 | 633 |
631 DCHECK(entry_ptr->writer || !entry_ptr->readers.empty() || | 634 DCHECK(entry_ptr->writer || !entry_ptr->readers.empty() || |
632 entry_ptr->will_process_pending_queue); | 635 entry_ptr->headers_transaction || |
636 entry_ptr->will_process_queued_transactions); | |
633 return OK; | 637 return OK; |
634 } | 638 } |
635 | 639 |
636 int HttpCache::AsyncDoomEntry(const std::string& key, Transaction* trans) { | 640 int HttpCache::AsyncDoomEntry(const std::string& key, Transaction* trans) { |
637 std::unique_ptr<WorkItem> item = | 641 std::unique_ptr<WorkItem> item = |
638 base::MakeUnique<WorkItem>(WI_DOOM_ENTRY, trans, nullptr); | 642 base::MakeUnique<WorkItem>(WI_DOOM_ENTRY, trans, nullptr); |
639 PendingOp* pending_op = GetPendingOp(key); | 643 PendingOp* pending_op = GetPendingOp(key); |
640 if (pending_op->writer) { | 644 if (pending_op->writer) { |
641 pending_op->pending_queue.push_back(std::move(item)); | 645 pending_op->pending_queue.push_back(std::move(item)); |
642 return ERR_IO_PENDING; | 646 return ERR_IO_PENDING; |
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678 DCHECK(entry->doomed); | 682 DCHECK(entry->doomed); |
679 DCHECK(entry->HasNoTransactions()); | 683 DCHECK(entry->HasNoTransactions()); |
680 | 684 |
681 auto it = doomed_entries_.find(entry); | 685 auto it = doomed_entries_.find(entry); |
682 DCHECK(it != doomed_entries_.end()); | 686 DCHECK(it != doomed_entries_.end()); |
683 doomed_entries_.erase(it); | 687 doomed_entries_.erase(it); |
684 } | 688 } |
685 | 689 |
686 HttpCache::ActiveEntry* HttpCache::FindActiveEntry(const std::string& key) { | 690 HttpCache::ActiveEntry* HttpCache::FindActiveEntry(const std::string& key) { |
687 auto it = active_entries_.find(key); | 691 auto it = active_entries_.find(key); |
688 return it != active_entries_.end() ? it->second.get() : NULL; | 692 return it != active_entries_.end() ? it->second.get() : nullptr; |
689 } | 693 } |
690 | 694 |
691 HttpCache::ActiveEntry* HttpCache::ActivateEntry( | 695 HttpCache::ActiveEntry* HttpCache::ActivateEntry( |
692 disk_cache::Entry* disk_entry) { | 696 disk_cache::Entry* disk_entry) { |
693 DCHECK(!FindActiveEntry(disk_entry->GetKey())); | 697 DCHECK(!FindActiveEntry(disk_entry->GetKey())); |
694 ActiveEntry* entry = new ActiveEntry(disk_entry); | 698 ActiveEntry* entry = new ActiveEntry(disk_entry); |
695 active_entries_[disk_entry->GetKey()] = base::WrapUnique(entry); | 699 active_entries_[disk_entry->GetKey()] = base::WrapUnique(entry); |
696 return entry; | 700 return entry; |
697 } | 701 } |
698 | 702 |
699 void HttpCache::DeactivateEntry(ActiveEntry* entry) { | 703 void HttpCache::DeactivateEntry(ActiveEntry* entry) { |
700 DCHECK(!entry->will_process_pending_queue); | 704 DCHECK(!entry->will_process_queued_transactions); |
701 DCHECK(!entry->doomed); | 705 DCHECK(!entry->doomed); |
702 DCHECK(entry->disk_entry); | 706 DCHECK(entry->disk_entry); |
703 DCHECK(entry->HasNoTransactions()); | 707 DCHECK(entry->HasNoTransactions()); |
704 | 708 |
705 std::string key = entry->disk_entry->GetKey(); | 709 std::string key = entry->disk_entry->GetKey(); |
706 if (key.empty()) | 710 if (key.empty()) |
707 return SlowDeactivateEntry(entry); | 711 return SlowDeactivateEntry(entry); |
708 | 712 |
709 auto it = active_entries_.find(key); | 713 auto it = active_entries_.find(key); |
710 DCHECK(it != active_entries_.end()); | 714 DCHECK(it != active_entries_.end()); |
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820 } | 824 } |
821 | 825 |
822 void HttpCache::DestroyEntry(ActiveEntry* entry) { | 826 void HttpCache::DestroyEntry(ActiveEntry* entry) { |
823 if (entry->doomed) { | 827 if (entry->doomed) { |
824 FinalizeDoomedEntry(entry); | 828 FinalizeDoomedEntry(entry); |
825 } else { | 829 } else { |
826 DeactivateEntry(entry); | 830 DeactivateEntry(entry); |
827 } | 831 } |
828 } | 832 } |
829 | 833 |
830 int HttpCache::AddTransactionToEntry(ActiveEntry* entry, Transaction* trans) { | 834 int HttpCache::AddTransactionToEntry(ActiveEntry* entry, |
835 Transaction* transaction) { | |
831 DCHECK(entry); | 836 DCHECK(entry); |
832 DCHECK(entry->disk_entry); | 837 DCHECK(entry->disk_entry); |
833 | 838 // Always add a new transaction to the queue to maintain FIFO order. |
834 // We implement a basic reader/writer lock for the disk cache entry. If | 839 entry->add_to_entry_queue.push_back(transaction); |
835 // there is already a writer, then everyone has to wait for the writer to | 840 ProcessQueuedTransactions(entry); |
836 // finish before they can access the cache entry. There can be multiple | 841 return ERR_IO_PENDING; |
837 // readers. | 842 } |
838 // | 843 |
839 // NOTE: If the transaction can only write, then the entry should not be in | 844 int HttpCache::DoneWithResponseHeaders(ActiveEntry* entry, |
840 // use (since any existing entry should have already been doomed). | 845 Transaction* transaction) { |
841 | 846 // If |transaction| is the current writer, do nothing. This can happen for |
842 if (entry->writer || entry->will_process_pending_queue) { | 847 // range requests since they can go back to headers phase after starting to |
843 entry->pending_queue.push_back(trans); | 848 // write. |
844 return ERR_IO_PENDING; | 849 if (entry->writer == transaction) |
845 } | 850 return OK; |
846 | 851 |
847 if (trans->mode() & Transaction::WRITE) { | 852 // Proceed only if |transaction| is a headers_transaction and not already a |
848 // transaction needs exclusive access to the entry | 853 // reader. |
849 if (entry->readers.empty()) { | 854 if (entry->headers_transaction != transaction) |
850 entry->writer = trans; | 855 return OK; |
jkarlin
2017/04/06 17:37:13
Once read-only transactions follow the normal path
shivanisha
2017/04/07 21:11:15
Yes, converted to DCHECK_EQ(entry->headers_transac
| |
851 } else { | 856 |
jkarlin
2017/04/06 17:37:13
DCHECK_EQ(entry->headers_transaction, transaction)
shivanisha
2017/04/07 21:11:16
done
| |
852 entry->pending_queue.push_back(trans); | 857 entry->headers_transaction = nullptr; |
853 return ERR_IO_PENDING; | 858 |
854 } | 859 entry->done_headers_queue.push_back(transaction); |
860 ProcessQueuedTransactions(entry); | |
861 return ERR_IO_PENDING; | |
862 } | |
863 | |
864 void HttpCache::RemoveAllQueuedTransactions(ActiveEntry* entry, | |
865 TransactionList* list) { | |
866 // Process done_headers_queue before add_to_entry_queue to maintain FIFO | |
867 // order. | |
868 for (auto* transaction : entry->done_headers_queue) | |
869 list->push_back(transaction); | |
870 entry->done_headers_queue.clear(); | |
871 | |
872 for (auto* transaction : entry->add_to_entry_queue) | |
873 list->push_back(transaction); | |
874 entry->add_to_entry_queue.clear(); | |
875 } | |
876 | |
877 void HttpCache::ProcessEntryFailure(ActiveEntry* entry) { | |
878 // Failure case is either writer failing to completely write the response to | |
879 // the cache or validating transaction received a non-304 response. | |
880 TransactionList list; | |
881 if (entry->HasNoActiveTransactions() && | |
882 !entry->will_process_queued_transactions) { | |
883 entry->disk_entry->Doom(); | |
884 RemoveAllQueuedTransactions(entry, &list); | |
885 DestroyEntry(entry); | |
855 } else { | 886 } else { |
856 // transaction needs read access to the entry | 887 DoomActiveEntry(entry->disk_entry->GetKey()); |
857 entry->readers.insert(trans); | 888 RemoveAllQueuedTransactions(entry, &list); |
858 } | 889 } |
859 | 890 // ERR_CACHE_RACE causes the transaction to restart the whole process. |
860 // We do this before calling EntryAvailable to force any further calls to | 891 for (auto* transaction : list) |
861 // AddTransactionToEntry to add their transaction to the pending queue, which | 892 transaction->io_callback().Run(net::ERR_CACHE_RACE); |
862 // ensures FIFO ordering. | 893 } |
863 if (!entry->writer && !entry->pending_queue.empty()) | 894 |
864 ProcessPendingQueue(entry); | 895 void HttpCache::ProcessQueuedTransactions(ActiveEntry* entry) { |
865 | 896 // Multiple readers may finish with an entry at once, so we want to batch up |
866 return OK; | 897 // calls to OnProcessQueuedTransactions. This flag also tells us that we |
867 } | 898 // should not delete the entry before OnProcessQueuedTransactions runs. |
868 | 899 if (entry->will_process_queued_transactions) |
869 void HttpCache::DoneWithEntry(ActiveEntry* entry, Transaction* trans, | 900 return; |
901 | |
902 entry->will_process_queued_transactions = true; | |
903 | |
904 // Post a task instead of invoking the io callback of another transaction here | |
905 // to avoid re-entrancy. | |
906 base::ThreadTaskRunnerHandle::Get()->PostTask( | |
907 FROM_HERE, | |
908 base::Bind(&HttpCache::OnProcessQueuedTransactions, GetWeakPtr(), entry)); | |
909 } | |
910 | |
911 void HttpCache::OnProcessQueuedTransactions(ActiveEntry* entry) { | |
912 entry->will_process_queued_transactions = false; | |
913 | |
914 // If no one is interested in this entry, then we can deactivate it. | |
915 if (entry->HasNoTransactions()) { | |
916 DestroyEntry(entry); | |
917 return; | |
918 } | |
919 | |
920 if (entry->done_headers_queue.empty() && entry->add_to_entry_queue.empty()) | |
921 return; | |
922 | |
923 // To maintain FIFO order of transactions, done_headers_queue should be | |
924 // processed first, and then add_to_entry_queue. | |
925 // If another transaction is writing the response, let validated transactions | |
926 // wait till the response is complete. If the response is not yet started, the | |
927 // done_headers_queue transaction should start writing it. | |
928 if (!entry->writer && !entry->done_headers_queue.empty()) { | |
929 ProcessDoneHeadersQueue(entry); | |
930 return; | |
jkarlin
2017/04/06 17:37:13
If you posttask the io callbacks (as mentioned in
shivanisha
2017/04/07 21:11:15
Removed the return
| |
931 } | |
932 | |
933 if (!entry->add_to_entry_queue.empty()) | |
934 ProcessAddToEntryQueue(entry); | |
935 } | |
936 | |
937 void HttpCache::ProcessAddToEntryQueue(ActiveEntry* entry) { | |
jkarlin
2017/04/06 17:37:13
Can you add a comment above this function definiti
shivanisha
2017/04/07 21:11:16
done
| |
938 if (entry->headers_transaction) { | |
939 // Note the entry may be new or may already have a response body written to | |
940 // it. In both cases, a transaction with write mode set, needs to wait | |
941 // because only one transaction is allowed to be validating at a time. | |
942 // If transaction is read-only and entry is not yet complete, then it | |
jkarlin
2017/04/06 17:37:13
Can remove the read-only comment.
shivanisha
2017/04/07 21:11:15
done
| |
943 // needs to wait. If entry is complete, it needs to wait because its | |
944 // possible that the headers_transaction dooms the entry if its not a match. | |
945 return; | |
946 } | |
947 | |
948 Transaction* transaction = entry->add_to_entry_queue.front(); | |
949 | |
950 // If a writer is present, read-only transactions cannot proceed. | |
951 if (entry->writer && !(transaction->mode() & Transaction::WRITE)) | |
952 return; | |
jkarlin
2017/04/06 17:37:13
This condition can go once we stop special-casing
shivanisha
2017/04/07 21:11:16
Yes, removed
| |
953 | |
954 entry->add_to_entry_queue.erase(entry->add_to_entry_queue.begin()); | |
955 | |
956 // This state may be reached either during the start of an entry or when the | |
957 // response is written or being written. | |
958 if (transaction->mode() & Transaction::WRITE) { | |
959 entry->headers_transaction = transaction; | |
960 } else { | |
961 // A read-only transaction can start reading the response. | |
jkarlin
2017/04/06 17:37:13
This condition can also go.
shivanisha
2017/04/07 21:11:15
Removed
| |
962 // If a read transaction is here, then it has to be an already created | |
963 // entry as the other case is already handled in the Transaction state | |
964 // machine. | |
965 entry->readers.insert(transaction); | |
966 | |
967 // More readers can join too. | |
968 // TODO (shivanisha@) Consider a loop instead of posting a task. | |
969 ProcessQueuedTransactions(entry); | |
970 } | |
971 | |
972 transaction->io_callback().Run(OK); | |
973 } | |
974 | |
975 void HttpCache::ProcessDoneHeadersQueue(ActiveEntry* entry) { | |
976 DCHECK(!entry->writer && !entry->done_headers_queue.empty()); | |
977 Transaction* transaction = entry->done_headers_queue.front(); | |
978 // If this transaction is responsible for writing the response body. | |
979 if (transaction->mode() & Transaction::WRITE) { | |
980 entry->writer = transaction; | |
981 } else { | |
982 // Response body is already written, convert to a reader. | |
983 auto return_val = entry->readers.insert(transaction); | |
984 DCHECK_EQ(return_val.second, true); | |
985 } | |
986 // Post another task to give a chance to more transactions to either join | |
987 // readers or another transaction to start parallel validation. | |
988 // TODO (shivanisha@) Consider a loop instead of posting a task. | |
jkarlin
2017/04/06 17:37:13
I assume the concern with looping is reentrancy?
shivanisha
2017/04/07 21:11:16
Introduced a loop instead of posting a task. As di
| |
989 ProcessQueuedTransactions(entry); | |
990 entry->done_headers_queue.erase(entry->done_headers_queue.begin()); | |
991 transaction->io_callback().Run(OK); | |
992 } | |
993 | |
994 bool HttpCache::CanTransactionWriteResponseHeaders(ActiveEntry* entry, | |
995 Transaction* transaction, | |
996 int response_code) const { | |
997 if (transaction != entry->headers_transaction) | |
998 return false; | |
999 | |
1000 // If its not a match then it should be the transaction responsible for | |
1001 // writing the response body. | |
1002 if (response_code != 304) { | |
1003 return !entry->writer && entry->done_headers_queue.empty(); | |
1004 } | |
1005 | |
1006 return true; | |
1007 } | |
1008 | |
1009 bool HttpCache::CanTransactionWriteResponseBody( | |
1010 ActiveEntry* entry, | |
1011 Transaction* transaction, | |
1012 const std::string& method) const { | |
1013 if (transaction == entry->writer) | |
1014 return true; | |
1015 | |
1016 if (method == "HEAD" || method == "DELETE") | |
1017 return false; | |
1018 | |
1019 // Check if transaction is about to start writing to the cache. | |
1020 | |
1021 // Transaction's mode may have been set to NONE if StopCaching was invoked. | |
1022 if (!(transaction->mode() & Transaction::WRITE || | |
1023 transaction->mode() == Transaction::NONE)) | |
jkarlin
2017/04/06 17:37:13
I think you want:
if ( !(transaction>mode() & Tra
shivanisha
2017/04/07 21:11:16
Not sure of the feedback here.
| |
1024 return false; | |
1025 | |
1026 if (transaction == entry->headers_transaction) | |
1027 return !entry->writer && entry->done_headers_queue.empty(); | |
jkarlin
2017/04/06 17:37:13
I don't understand this conditional. Can you add a
shivanisha
2017/04/07 21:11:16
This and the below conditions are actually doing m
| |
1028 | |
1029 // Check the first of done_headers_queue, since the rest should anyways be | |
1030 // READ mode transactions as they would be a result of validation match. | |
1031 if (transaction == entry->done_headers_queue.front()) | |
1032 return !entry->writer; | |
1033 | |
1034 return false; | |
1035 } | |
1036 | |
1037 void HttpCache::DoneWithEntry(ActiveEntry* entry, | |
1038 Transaction* transaction, | |
870 bool cancel) { | 1039 bool cancel) { |
871 // If we already posted a task to move on to the next transaction and this was | 1040 // Transaction is waiting in the done_headers_queue. |
872 // the writer, there is nothing to cancel. | 1041 auto i = std::find(entry->done_headers_queue.begin(), |
jkarlin
2017/04/06 17:37:13
s/i/it/
shivanisha
2017/04/07 21:11:16
done
| |
873 if (entry->will_process_pending_queue && entry->readers.empty()) | 1042 entry->done_headers_queue.end(), transaction); |
874 return; | 1043 if (i != entry->done_headers_queue.end()) { |
875 | 1044 entry->done_headers_queue.erase(i); |
876 if (entry->writer) { | 1045 if (cancel) |
877 DCHECK(trans == entry->writer); | 1046 ProcessEntryFailure(entry); |
878 | 1047 return; |
1048 } | |
1049 | |
1050 // Transaction is removed in the headers phase. | |
1051 if (transaction == entry->headers_transaction) { | |
1052 // If the response is not written (cancel is true), consider it a failure. | |
1053 DoneWritingToEntry(entry, !cancel, transaction); | |
1054 return; | |
1055 } | |
1056 | |
1057 // Transaction is removed in the writing phase. | |
1058 if (transaction == entry->writer) { | |
879 // Assume there was a failure. | 1059 // Assume there was a failure. |
880 bool success = false; | 1060 bool success = false; |
881 if (cancel) { | 1061 if (cancel) { |
882 DCHECK(entry->disk_entry); | 1062 DCHECK(entry->disk_entry); |
883 // This is a successful operation in the sense that we want to keep the | 1063 // This is a successful operation in the sense that we want to keep the |
884 // entry. | 1064 // entry. |
885 success = trans->AddTruncatedFlag(); | 1065 success = transaction->AddTruncatedFlag(); |
886 // The previous operation may have deleted the entry. | 1066 // The previous operation may have deleted the entry. |
887 if (!trans->entry()) | 1067 if (!transaction->entry()) |
888 return; | 1068 return; |
889 } | 1069 } |
890 DoneWritingToEntry(entry, success); | 1070 DoneWritingToEntry(entry, success, transaction); |
891 } else { | 1071 return; |
892 DoneReadingFromEntry(entry, trans); | 1072 } |
893 } | 1073 |
894 } | 1074 // Transaction is reading from the entry. |
895 | 1075 DoneReadingFromEntry(entry, transaction); |
896 void HttpCache::DoneWritingToEntry(ActiveEntry* entry, bool success) { | 1076 } |
897 DCHECK(entry->readers.empty()); | 1077 |
898 | 1078 void HttpCache::DoneWritingToEntry(ActiveEntry* entry, |
899 entry->writer = NULL; | 1079 bool success, |
900 | 1080 Transaction* transaction) { |
901 if (success) { | 1081 DCHECK(transaction == entry->writer || |
902 ProcessPendingQueue(entry); | 1082 transaction == entry->headers_transaction); |
903 } else { | 1083 |
904 DCHECK(!entry->will_process_pending_queue); | 1084 if (transaction == entry->writer) |
905 | 1085 entry->writer = nullptr; |
906 // We failed to create this entry. | 1086 else |
907 TransactionList pending_queue; | 1087 entry->headers_transaction = nullptr; |
908 pending_queue.swap(entry->pending_queue); | 1088 |
909 | 1089 // If writer fails, all transactions restart the headers_transaction. |
910 entry->disk_entry->Doom(); | 1090 if (!success && entry->headers_transaction) { |
911 DestroyEntry(entry); | 1091 entry->headers_transaction->SetValidatingCannotProceed(); |
912 | 1092 entry->headers_transaction = nullptr; |
913 // We need to do something about these pending entries, which now need to | 1093 DCHECK(entry->HasNoActiveTransactions()); |
914 // be added to a new entry. | 1094 } |
915 while (!pending_queue.empty()) { | 1095 if (!success) |
916 // ERR_CACHE_RACE causes the transaction to restart the whole process. | 1096 ProcessEntryFailure(entry); |
917 pending_queue.front()->io_callback().Run(ERR_CACHE_RACE); | 1097 else |
918 pending_queue.pop_front(); | 1098 ProcessQueuedTransactions(entry); |
919 } | 1099 } |
920 } | 1100 |
921 } | 1101 void HttpCache::DoneReadingFromEntry(ActiveEntry* entry, |
922 | 1102 Transaction* transaction) { |
923 void HttpCache::DoneReadingFromEntry(ActiveEntry* entry, Transaction* trans) { | |
924 DCHECK(!entry->writer); | 1103 DCHECK(!entry->writer); |
925 | 1104 auto it = entry->readers.find(transaction); |
jkarlin
2017/04/06 17:37:13
Can you add a TODO that this is a linear operation
shivanisha
2017/04/07 21:11:15
readers is an unordered_set so average case is not
| |
926 auto it = entry->readers.find(trans); | |
927 DCHECK(it != entry->readers.end()); | 1105 DCHECK(it != entry->readers.end()); |
928 | |
929 entry->readers.erase(it); | 1106 entry->readers.erase(it); |
930 | 1107 |
931 ProcessPendingQueue(entry); | 1108 ProcessQueuedTransactions(entry); |
932 } | |
933 | |
934 void HttpCache::ConvertWriterToReader(ActiveEntry* entry) { | |
935 DCHECK(entry->writer); | |
936 DCHECK(entry->writer->mode() == Transaction::READ_WRITE); | |
937 DCHECK(entry->readers.empty()); | |
938 | |
939 Transaction* trans = entry->writer; | |
940 | |
941 entry->writer = NULL; | |
942 entry->readers.insert(trans); | |
943 | |
944 ProcessPendingQueue(entry); | |
945 } | 1109 } |
946 | 1110 |
947 LoadState HttpCache::GetLoadStateForPendingTransaction( | 1111 LoadState HttpCache::GetLoadStateForPendingTransaction( |
948 const Transaction* trans) { | 1112 const Transaction* trans) { |
949 auto i = active_entries_.find(trans->key()); | 1113 auto i = active_entries_.find(trans->key()); |
950 if (i == active_entries_.end()) { | 1114 if (i == active_entries_.end()) { |
951 // If this is really a pending transaction, and it is not part of | 1115 // If this is really a pending transaction, and it is not part of |
952 // active_entries_, we should be creating the backend or the entry. | 1116 // active_entries_, we should be creating the backend or the entry. |
953 return LOAD_STATE_WAITING_FOR_CACHE; | 1117 return LOAD_STATE_WAITING_FOR_CACHE; |
954 } | 1118 } |
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984 | 1148 |
985 for (auto k = doomed_entries_.begin(); k != doomed_entries_.end() && !found; | 1149 for (auto k = doomed_entries_.begin(); k != doomed_entries_.end() && !found; |
986 ++k) { | 1150 ++k) { |
987 found = RemovePendingTransactionFromEntry(k->first, trans); | 1151 found = RemovePendingTransactionFromEntry(k->first, trans); |
988 } | 1152 } |
989 | 1153 |
990 DCHECK(found) << "Pending transaction not found"; | 1154 DCHECK(found) << "Pending transaction not found"; |
991 } | 1155 } |
992 | 1156 |
993 bool HttpCache::RemovePendingTransactionFromEntry(ActiveEntry* entry, | 1157 bool HttpCache::RemovePendingTransactionFromEntry(ActiveEntry* entry, |
994 Transaction* trans) { | 1158 Transaction* transaction) { |
995 TransactionList& pending_queue = entry->pending_queue; | 1159 TransactionList& add_to_entry_queue = entry->add_to_entry_queue; |
996 | 1160 |
997 auto j = find(pending_queue.begin(), pending_queue.end(), trans); | 1161 auto j = |
998 if (j == pending_queue.end()) | 1162 find(add_to_entry_queue.begin(), add_to_entry_queue.end(), transaction); |
1163 if (j == add_to_entry_queue.end()) | |
999 return false; | 1164 return false; |
1000 | 1165 |
1001 pending_queue.erase(j); | 1166 add_to_entry_queue.erase(j); |
1002 return true; | 1167 return true; |
1003 } | 1168 } |
1004 | 1169 |
1005 bool HttpCache::RemovePendingTransactionFromPendingOp(PendingOp* pending_op, | 1170 bool HttpCache::RemovePendingTransactionFromPendingOp(PendingOp* pending_op, |
1006 Transaction* trans) { | 1171 Transaction* trans) { |
1007 if (pending_op->writer->Matches(trans)) { | 1172 if (pending_op->writer->Matches(trans)) { |
1008 pending_op->writer->ClearTransaction(); | 1173 pending_op->writer->ClearTransaction(); |
1009 pending_op->writer->ClearEntry(); | 1174 pending_op->writer->ClearEntry(); |
1010 return true; | 1175 return true; |
1011 } | 1176 } |
1012 WorkItemList& pending_queue = pending_op->pending_queue; | 1177 WorkItemList& pending_queue = pending_op->pending_queue; |
1013 | 1178 |
1014 for (auto it = pending_queue.begin(); it != pending_queue.end(); ++it) { | 1179 for (auto it = pending_queue.begin(); it != pending_queue.end(); ++it) { |
1015 if ((*it)->Matches(trans)) { | 1180 if ((*it)->Matches(trans)) { |
1016 pending_queue.erase(it); | 1181 pending_queue.erase(it); |
1017 return true; | 1182 return true; |
1018 } | 1183 } |
1019 } | 1184 } |
1020 return false; | 1185 return false; |
1021 } | 1186 } |
1022 | 1187 |
1023 void HttpCache::ProcessPendingQueue(ActiveEntry* entry) { | |
1024 // Multiple readers may finish with an entry at once, so we want to batch up | |
1025 // calls to OnProcessPendingQueue. This flag also tells us that we should | |
1026 // not delete the entry before OnProcessPendingQueue runs. | |
1027 if (entry->will_process_pending_queue) | |
1028 return; | |
1029 entry->will_process_pending_queue = true; | |
1030 | |
1031 base::ThreadTaskRunnerHandle::Get()->PostTask( | |
1032 FROM_HERE, | |
1033 base::Bind(&HttpCache::OnProcessPendingQueue, GetWeakPtr(), entry)); | |
1034 } | |
1035 | |
1036 void HttpCache::OnProcessPendingQueue(ActiveEntry* entry) { | |
1037 entry->will_process_pending_queue = false; | |
1038 DCHECK(!entry->writer); | |
1039 | |
1040 // If no one is interested in this entry, then we can deactivate it. | |
1041 if (entry->HasNoTransactions()) { | |
1042 DestroyEntry(entry); | |
1043 return; | |
1044 } | |
1045 | |
1046 if (entry->pending_queue.empty()) | |
1047 return; | |
1048 | |
1049 // Promote next transaction from the pending queue. | |
1050 Transaction* next = entry->pending_queue.front(); | |
1051 if ((next->mode() & Transaction::WRITE) && !entry->readers.empty()) | |
1052 return; // Have to wait. | |
1053 | |
1054 entry->pending_queue.erase(entry->pending_queue.begin()); | |
1055 | |
1056 int rv = AddTransactionToEntry(entry, next); | |
1057 if (rv != ERR_IO_PENDING) { | |
1058 next->io_callback().Run(rv); | |
1059 } | |
1060 } | |
1061 | |
1062 void HttpCache::OnIOComplete(int result, PendingOp* pending_op) { | 1188 void HttpCache::OnIOComplete(int result, PendingOp* pending_op) { |
1063 WorkItemOperation op = pending_op->writer->operation(); | 1189 WorkItemOperation op = pending_op->writer->operation(); |
1064 | 1190 |
1065 // Completing the creation of the backend is simpler than the other cases. | 1191 // Completing the creation of the backend is simpler than the other cases. |
1066 if (op == WI_CREATE_BACKEND) | 1192 if (op == WI_CREATE_BACKEND) |
1067 return OnBackendCreated(result, pending_op); | 1193 return OnBackendCreated(result, pending_op); |
1068 | 1194 |
1069 std::unique_ptr<WorkItem> item = std::move(pending_op->writer); | 1195 std::unique_ptr<WorkItem> item = std::move(pending_op->writer); |
1070 bool fail_requests = false; | 1196 bool fail_requests = false; |
1071 | 1197 |
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1196 building_backend_ = false; | 1322 building_backend_ = false; |
1197 DeletePendingOp(pending_op); | 1323 DeletePendingOp(pending_op); |
1198 } | 1324 } |
1199 | 1325 |
1200 // The cache may be gone when we return from the callback. | 1326 // The cache may be gone when we return from the callback. |
1201 if (!item->DoCallback(result, disk_cache_.get())) | 1327 if (!item->DoCallback(result, disk_cache_.get())) |
1202 item->NotifyTransaction(result, NULL); | 1328 item->NotifyTransaction(result, NULL); |
1203 } | 1329 } |
1204 | 1330 |
1205 } // namespace net | 1331 } // namespace net |
OLD | NEW |