1 | /* -*- C++ -*- |
2 | |
3 | This file implements the DependencyPolicy class. |
4 | |
5 | $ Author: Mirko Boehm $ |
6 | $ Copyright: (C) 2004-2013 Mirko Boehm $ |
7 | $ Contact: mirko@kde.org |
8 | http://www.kde.org |
9 | http://creative-destruction.me $ |
10 | |
11 | This library is free software; you can redistribute it and/or |
12 | modify it under the terms of the GNU Library General Public |
13 | License as published by the Free Software Foundation; either |
14 | version 2 of the License, or (at your option) any later version. |
15 | |
16 | This library is distributed in the hope that it will be useful, |
17 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
18 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
19 | Library General Public License for more details. |
20 | |
21 | You should have received a copy of the GNU Library General Public License |
22 | along with this library; see the file COPYING.LIB. If not, write to |
23 | the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, |
24 | Boston, MA 02110-1301, USA. |
25 | |
26 | $Id: DebuggingAids.cpp 20 2005-08-08 21:02:51Z mirko $ |
27 | */ |
28 | |
29 | #ifndef DEPENDENCYPOLICY_H |
30 | #define DEPENDENCYPOLICY_H |
31 | |
32 | template <typename T> class QList; |
33 | |
34 | #include "QueuePolicy.h" |
35 | |
36 | namespace ThreadWeaver { |
37 | |
38 | /** DependencyPolicy implements the way dependencies between Jobs are handled. |
39 | |
40 | To declare that Job B can only be executed when Job A is finished, |
41 | call addDependency. |
42 | |
43 | Be aware of circular dependencies. All dependencies on a Job will be |
44 | removed if the Job object is destructed. |
45 | |
46 | JobSequence uses dependencies to implement the ordered execution of |
47 | the sequence elements. |
48 | */ |
49 | class THREADWEAVER_EXPORT DependencyPolicy : public QueuePolicy |
50 | { |
51 | public: |
52 | /** Destructor. */ |
53 | ~DependencyPolicy(); |
54 | |
55 | /** Add jobB as a dependency of jobA. |
56 | jobA will only be executed after jobB has been successfully processed. |
57 | @param jobA the depending job |
58 | @param jobB the job jobA depends on |
59 | */ |
60 | void addDependency( Job* jobA, Job* jobB ); |
61 | |
62 | /** Remove dependency. |
63 | |
64 | The dependency of jobA on jobB is removed. If no dependencies are |
65 | left for jobA, canRun will return true. |
66 | |
67 | Returns false if the given object is not dependency of this job. |
68 | |
69 | This function is inefficient, and should be used only to abort |
70 | execution of a job. |
71 | |
72 | @param jobA the depending job |
73 | @param jobB the job jobA depends on |
74 | @return true if dependency existed, false otherwise |
75 | */ |
76 | bool removeDependency( Job* jobA, Job* jobB ); |
77 | |
78 | /** Resolve all dependencies. |
79 | This method is called after the Job has been finished, or |
80 | when it is deleted without being executed (performed by the |
81 | destructor). |
82 | The method will remove all entries stating that another Job |
83 | depends on this one. |
84 | */ |
85 | void resolveDependencies ( Job* ); |
86 | |
87 | /** Retrieve a list of dependencies of this job. */ |
88 | QList<Job*> getDependencies( Job* ) const; |
89 | |
90 | // FIXME add factory method for singleton creation |
91 | static DependencyPolicy& instance(); |
92 | |
93 | bool canRun( Job* ); |
94 | |
95 | void free( Job* ); |
96 | |
97 | void release( Job* ); |
98 | |
99 | void destructed( Job* ); |
100 | |
101 | protected: |
102 | /** Query whether the job has an unresolved dependency. |
103 | In case it does, the policy will return false from canRun(). |
104 | */ |
105 | bool hasUnresolvedDependencies( Job* ) const; |
106 | |
107 | DependencyPolicy(); |
108 | |
109 | private: |
110 | class Private; |
111 | Private * const d; |
112 | |
113 | public: |
114 | /** This method should be useful for debugging purposes. */ |
115 | void dumpJobDependencies(); |
116 | }; |
117 | |
118 | } |
119 | |
120 | #endif |
121 | |