1 /*
2 * Copyright (C) 2013 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26 #ifndef SQLTransactionStateMachine_h
27 #define SQLTransactionStateMachine_h
28
29 #include "modules/webdatabase/SQLTransactionState.h"
30 #include "wtf/ThreadSafeRefCounted.h"
31
32 namespace WebCore {
33
34 template<typename T>
35 class SQLTransactionStateMachine {
36 public:
~SQLTransactionStateMachine()37 virtual ~SQLTransactionStateMachine() { }
38
39 protected:
40 SQLTransactionStateMachine();
41
42 typedef SQLTransactionState (T::* StateFunction)();
43 virtual StateFunction stateFunctionFor(SQLTransactionState) = 0;
44
45 void setStateToRequestedState();
46 void runStateMachine();
47
48 SQLTransactionState m_nextState;
49 SQLTransactionState m_requestedState;
50
51 #ifndef NDEBUG
52 // The state audit trail (i.e. bread crumbs) keeps track of up to the last
53 // s_sizeOfStateAuditTrail states that the state machine enters. The audit
54 // trail is updated before entering each state. This is for debugging use
55 // only.
56 static const int s_sizeOfStateAuditTrail = 20;
57 int m_nextStateAuditEntry;
58 SQLTransactionState m_stateAuditTrail[s_sizeOfStateAuditTrail];
59 #endif
60 };
61
62 #if !LOG_DISABLED
63 extern const char* nameForSQLTransactionState(SQLTransactionState);
64 #endif
65
66 template<typename T>
SQLTransactionStateMachine()67 SQLTransactionStateMachine<T>::SQLTransactionStateMachine()
68 : m_nextState(SQLTransactionState::Idle)
69 , m_requestedState(SQLTransactionState::Idle)
70 #ifndef NDEBUG
71 , m_nextStateAuditEntry(0)
72 #endif
73 {
74 #ifndef NDEBUG
75 for (int i = 0; i < s_sizeOfStateAuditTrail; i++)
76 m_stateAuditTrail[i] = SQLTransactionState::NumberOfStates;
77 #endif
78 }
79
80 template<typename T>
setStateToRequestedState()81 void SQLTransactionStateMachine<T>::setStateToRequestedState()
82 {
83 ASSERT(m_nextState == SQLTransactionState::Idle);
84 ASSERT(m_requestedState != SQLTransactionState::Idle);
85 m_nextState = m_requestedState;
86 m_requestedState = SQLTransactionState::Idle;
87 }
88
89 template<typename T>
runStateMachine()90 void SQLTransactionStateMachine<T>::runStateMachine()
91 {
92 ASSERT(SQLTransactionState::End < SQLTransactionState::Idle);
93 while (m_nextState > SQLTransactionState::Idle) {
94 ASSERT(m_nextState < SQLTransactionState::NumberOfStates);
95 StateFunction stateFunction = stateFunctionFor(m_nextState);
96 ASSERT(stateFunction);
97
98 #ifndef NDEBUG
99 m_stateAuditTrail[m_nextStateAuditEntry] = m_nextState;
100 m_nextStateAuditEntry = (m_nextStateAuditEntry + 1) % s_sizeOfStateAuditTrail;
101 #endif
102 m_nextState = (static_cast<T*>(this)->*stateFunction)();
103 }
104 }
105
106 } // namespace WebCore
107
108 #endif // SQLTransactionStateMachine_h
109