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21 
22 
23 
24 // MARKER(update_precomp.py): autogen include statement, do not remove
25 #include "precompiled_unotools.hxx"
26 #include "unotools/readwritemutexguard.hxx"
27 #include <tools/debug.hxx>
28 
29 
30 namespace utl {
31 
ReadWriteGuard(ReadWriteMutex & rMutexP,sal_Int32 nRequestMode)32 ReadWriteGuard::ReadWriteGuard( ReadWriteMutex& rMutexP,
33             sal_Int32 nRequestMode )
34         : rMutex( rMutexP )
35 {
36     // don't do anything until a pending write completed (or another
37     // ReadWriteGuard leaves the ctor phase)
38     ::osl::MutexGuard aGuard( rMutex.pWriteMutex );
39     nMode = nRequestMode;
40     if ( nMode & ReadWriteGuardMode::nWrite )
41     {
42         rMutex.pWriteMutex->acquire();
43         // wait for any read to complete
44 // TODO: set up a waiting thread instead of a loop
45         sal_Bool bWait = sal_True;
46         do
47         {
48             rMutex.pMutex->acquire();
49             bWait = (rMutex.nReadCount != 0);
50             if ( nMode & ReadWriteGuardMode::nCriticalChange )
51                 bWait |= (rMutex.nBlockCriticalCount != 0);
52             rMutex.pMutex->release();
53         } while ( bWait );
54     }
55     else if ( nMode & ReadWriteGuardMode::nBlockCritical )
56     {
57         rMutex.pMutex->acquire();
58         ++rMutex.nBlockCriticalCount;
59         rMutex.pMutex->release();
60     }
61     else
62     {
63         rMutex.pMutex->acquire();
64         ++rMutex.nReadCount;
65         rMutex.pMutex->release();
66     }
67 }
68 
69 
~ReadWriteGuard()70 ReadWriteGuard::~ReadWriteGuard()
71 {
72     if ( nMode & ReadWriteGuardMode::nWrite )
73         rMutex.pWriteMutex->release();
74     else if ( nMode & ReadWriteGuardMode::nBlockCritical )
75     {
76         rMutex.pMutex->acquire();
77         --rMutex.nBlockCriticalCount;
78         rMutex.pMutex->release();
79     }
80     else
81     {
82         rMutex.pMutex->acquire();
83         --rMutex.nReadCount;
84         rMutex.pMutex->release();
85     }
86 }
87 
88 
changeReadToWrite()89 void ReadWriteGuard::changeReadToWrite()
90 {
91     sal_Bool bOk = !(nMode & (ReadWriteGuardMode::nWrite | ReadWriteGuardMode::nBlockCritical));
92     DBG_ASSERT( bOk, "ReadWriteGuard::changeReadToWrite: can't" );
93     if ( bOk )
94     {
95         // MUST release read before acquiring write mutex or dead lock would
96         // occur if there was a write in another thread waiting for this read
97         // to complete.
98         rMutex.pMutex->acquire();
99         --rMutex.nReadCount;
100         rMutex.pMutex->release();
101 
102         rMutex.pWriteMutex->acquire();
103         nMode |= ReadWriteGuardMode::nWrite;
104         // wait for any other read to complete
105 // TODO: set up a waiting thread instead of a loop
106         sal_Bool bWait = sal_True;
107         do
108         {
109             rMutex.pMutex->acquire();
110             bWait = (rMutex.nReadCount != 0);
111             rMutex.pMutex->release();
112         } while ( bWait );
113     }
114 }
115 
116 }   // namespace utl
117