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
32namespace blink {
33
34template<typename T>
35class SQLTransactionStateMachine {
36public:
37    virtual ~SQLTransactionStateMachine() { }
38
39protected:
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#if ENABLE(ASSERT)
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
63extern const char* nameForSQLTransactionState(SQLTransactionState);
64#endif
65
66template<typename T>
67SQLTransactionStateMachine<T>::SQLTransactionStateMachine()
68    : m_nextState(SQLTransactionState::Idle)
69    , m_requestedState(SQLTransactionState::Idle)
70#if ENABLE(ASSERT)
71    , m_nextStateAuditEntry(0)
72#endif
73{
74#if ENABLE(ASSERT)
75    for (int i = 0; i < s_sizeOfStateAuditTrail; i++)
76        m_stateAuditTrail[i] = SQLTransactionState::NumberOfStates;
77#endif
78}
79
80template<typename T>
81void 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
89template<typename T>
90void 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#if ENABLE(ASSERT)
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 blink
107
108#endif // SQLTransactionStateMachine_h
109