beserved/bt_fs/readerWriter.c

21 bool initManagedData(bt_managed_data *data)
23 	data->readCount = 0;
24 	data->writeCount = 0;
26 	data->readCountVar = 0;
27 	data->writeCountVar = 0;
28 	data->readerQueueVar = 0;
29 	data->readerVar = 0;
30 	data->writerVar = 0;
32 	if ((data->readCountSem = create_sem(1, "Read Counter")) < 0)
35 	if ((data->writeCountSem = create_sem(1, "Write Counter")) < 0)
37 		delete_sem(data->readCountSem);
41 	if ((data->readerQueue = create_sem(1, "Read Queue")) < 0)
43 		delete_sem(data->writeCountSem);
44 		delete_sem(data->readCountSem);
48 	if ((data->reader = create_sem(1, "Single Reader")) < 0)
50 		delete_sem(data->readerQueue);
51 		delete_sem(data->writeCountSem);
52 		delete_sem(data->readCountSem);
56 	if ((data->writer = create_sem(1, "Writer")) < 0)
58 		delete_sem(data->reader);
59 		delete_sem(data->readerQueue);
60 		delete_sem(data->writeCountSem);
61 		delete_sem(data->readCountSem);
65 	set_sem_owner(data->readCountSem, B_SYSTEM_TEAM);
66 	set_sem_owner(data->writeCountSem, B_SYSTEM_TEAM);
67 	set_sem_owner(data->readerQueue, B_SYSTEM_TEAM);
68 	set_sem_owner(data->reader, B_SYSTEM_TEAM);
69 	set_sem_owner(data->writer, B_SYSTEM_TEAM);
74 void closeManagedData(bt_managed_data *data)
76 	data->readCount = data->writeCount = 0;
78 	delete_sem(data->writer);
79 	delete_sem(data->reader);
80 	delete_sem(data->readerQueue);
81 	delete_sem(data->writeCountSem);
82 	delete_sem(data->readCountSem);
85 void beginReading(bt_managed_data *data)
87 	btLock(data->readerQueue, &data->readerQueueVar);
88 	btLock(data->reader, &data->readerVar);
89 	btLock(data->readCountSem, &data->readCountVar);
91 	data->readCount++;
92 	if (data->readCount == 1)
93 		btLock(data->writer, &data->writerVar);
95 	btUnlock(data->readCountSem, &data->readCountVar);
96 	btUnlock(data->reader, &data->readerVar);
97 	btUnlock(data->readerQueue, &data->readerQueueVar);
100 void endReading(bt_managed_data *data)
102 	btLock(data->readCountSem, &data->readCountVar);
104 	data->readCount--;
105 	if (data->readCount == 0)
106 		btUnlock(data->writer, &data->writerVar);
108 	btUnlock(data->readCountSem, &data->readCountVar);
111 void beginWriting(bt_managed_data *data)
113 	btLock(data->writeCountSem, &data->writeCountVar);
115 	data->writeCount++;
116 	if (data->writeCount == 1)
117 		btLock(data->reader, &data->readerVar);
119 	btUnlock(data->writeCountSem, &data->writeCountVar);
120 	btLock(data->writer, &data->writerVar);
123 void endWriting(bt_managed_data *data)
125 	btUnlock(data->writer, &data->writerVar);
126 	btLock(data->writeCountSem, &data->writeCountVar);
128 	data->writeCount--;
129 	if (data->writeCount == 0)
130 		btUnlock(data->reader, &data->readerVar);
132 	btUnlock(data->writeCountSem, &data->writeCountVar);