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Thread safety experiments.

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This commit is contained in:
David Reid
2018-08-26 19:00:36 +10:00
parent 36ec24cda6
commit ce5ab2c17e
1 changed files with 32 additions and 20 deletions
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research/mal_ring_buffer.h
+32 -20
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@@ -54,8 +54,8 @@ typedef struct
mal_uint32 subbufferSizeInBytes;
mal_uint32 subbufferCount;
mal_uint32 subbufferStrideInBytes;
mal_uint32 readOffset; /* Most significant bit is the loop flag. Lower 31 bits contains the actual offset in bytes. */
mal_uint32 writeOffset; /* Most significant bit is the loop flag. Lower 31 bits contains the actual offset in bytes. */
volatile mal_uint32 readOffset; /* Most significant bit is the loop flag. Lower 31 bits contains the actual offset in bytes. */
volatile mal_uint32 writeOffset; /* Most significant bit is the loop flag. Lower 31 bits contains the actual offset in bytes. */
mal_bool32 ownsBuffer : 1; /* Used to know whether or not mini_al is responsible for free()-ing the buffer. */
mal_bool32 clearOnWriteAcquire : 1; /* When set, clears the acquired write buffer before returning from mal_rb_acquire_write(). */
} mal_rb;
@@ -168,13 +168,15 @@ mal_result mal_rb_acquire_read(mal_rb* pRB, size_t* pSizeInBytes, void** ppBuffe
}
// The returned buffer should never move ahead of the write pointer.
volatile mal_uint32 writeOffset = pRB->writeOffset;
mal_uint32 writeOffsetInBytes;
mal_uint32 writeOffsetLoopFlag;
mal_rb__deconstruct_offset(pRB->writeOffset, &writeOffsetInBytes, &writeOffsetLoopFlag);
mal_rb__deconstruct_offset(writeOffset, &writeOffsetInBytes, &writeOffsetLoopFlag);
volatile mal_uint32 readOffset = pRB->readOffset;
mal_uint32 readOffsetInBytes;
mal_uint32 readOffsetLoopFlag;
mal_rb__deconstruct_offset(pRB->readOffset, &readOffsetInBytes, &readOffsetLoopFlag);
mal_rb__deconstruct_offset(readOffset, &readOffsetInBytes, &readOffsetLoopFlag);
// The number of bytes available depends on whether or not the read and write pointers are on the same loop iteration. If so, we
// can only read up to the write pointer. If not, we can only read up to the end of the buffer.
@@ -207,9 +209,10 @@ mal_result mal_rb_commit_read(mal_rb* pRB, size_t sizeInBytes, void* pBufferOut)
return MAL_INVALID_ARGS;
}
volatile mal_uint32 readOffset = pRB->readOffset;
mal_uint32 readOffsetInBytes;
mal_uint32 readOffsetLoopFlag;
mal_rb__deconstruct_offset(pRB->readOffset, &readOffsetInBytes, &readOffsetLoopFlag);
mal_rb__deconstruct_offset(readOffset, &readOffsetInBytes, &readOffsetLoopFlag);
// Check that sizeInBytes is correct. It should never go beyond the end of the buffer.
mal_uint32 newReadOffsetInBytes = (mal_uint32)(readOffsetInBytes + sizeInBytes);
@@ -235,13 +238,15 @@ mal_result mal_rb_acquire_write(mal_rb* pRB, size_t* pSizeInBytes, void** ppBuff
}
// The returned buffer should never overtake the read buffer.
volatile mal_uint32 readOffset = pRB->readOffset;
mal_uint32 readOffsetInBytes;
mal_uint32 readOffsetLoopFlag;
mal_rb__deconstruct_offset(pRB->readOffset, &readOffsetInBytes, &readOffsetLoopFlag);
mal_rb__deconstruct_offset(readOffset, &readOffsetInBytes, &readOffsetLoopFlag);
volatile mal_uint32 writeOffset = pRB->writeOffset;
mal_uint32 writeOffsetInBytes;
mal_uint32 writeOffsetLoopFlag;
mal_rb__deconstruct_offset(pRB->writeOffset, &writeOffsetInBytes, &writeOffsetLoopFlag);
mal_rb__deconstruct_offset(writeOffset, &writeOffsetInBytes, &writeOffsetLoopFlag);
// In the case of writing, if the write pointer and the read pointer are on the same loop iteration we can only
// write up to the end of the buffer. Otherwise we can only write up to the read pointer. The write pointer should
@@ -280,9 +285,10 @@ mal_result mal_rb_commit_write(mal_rb* pRB, size_t sizeInBytes, void* pBufferOut
return MAL_INVALID_ARGS;
}
volatile mal_uint32 writeOffset = pRB->writeOffset;
mal_uint32 writeOffsetInBytes;
mal_uint32 writeOffsetLoopFlag;
mal_rb__deconstruct_offset(pRB->writeOffset, &writeOffsetInBytes, &writeOffsetLoopFlag);
mal_rb__deconstruct_offset(writeOffset, &writeOffsetInBytes, &writeOffsetLoopFlag);
// Check that sizeInBytes is correct. It should never go beyond the end of the buffer.
mal_uint32 newWriteOffsetInBytes = (mal_uint32)(writeOffsetInBytes + sizeInBytes);
@@ -307,13 +313,15 @@ mal_result mal_rb_seek_read(mal_rb* pRB, size_t offsetInBytes)
return MAL_INVALID_ARGS;
}
volatile mal_uint32 readOffset = pRB->readOffset;
mal_uint32 readOffsetInBytes;
mal_uint32 readOffsetLoopFlag;
mal_rb__deconstruct_offset(pRB->readOffset, &readOffsetInBytes, &readOffsetLoopFlag);
mal_rb__deconstruct_offset(readOffset, &readOffsetInBytes, &readOffsetLoopFlag);
volatile mal_uint32 writeOffset = pRB->writeOffset;
mal_uint32 writeOffsetInBytes;
mal_uint32 writeOffsetLoopFlag;
mal_rb__deconstruct_offset(pRB->writeOffset, &writeOffsetInBytes, &writeOffsetLoopFlag);
mal_rb__deconstruct_offset(writeOffset, &writeOffsetInBytes, &writeOffsetLoopFlag);
mal_uint32 newReadOffsetInBytes = readOffsetInBytes;
mal_uint32 newReadOffsetLoopFlag = readOffsetLoopFlag;
@@ -323,15 +331,15 @@ mal_result mal_rb_seek_read(mal_rb* pRB, size_t offsetInBytes)
if ((readOffsetInBytes + offsetInBytes) > writeOffsetInBytes) {
newReadOffsetInBytes = writeOffsetInBytes;
} else {
newReadOffsetInBytes = (readOffsetInBytes + offsetInBytes);
newReadOffsetInBytes = (mal_uint32)(readOffsetInBytes + offsetInBytes);
}
} else {
// May end up looping.
if ((readOffsetInBytes + offsetInBytes) >= pRB->subbufferSizeInBytes) {
newReadOffsetInBytes = (readOffsetInBytes + offsetInBytes) - pRB->subbufferSizeInBytes;
newReadOffsetInBytes = (mal_uint32)(readOffsetInBytes + offsetInBytes) - pRB->subbufferSizeInBytes;
newReadOffsetLoopFlag ^= 0x80000000; /* <-- Looped. */
} else {
newReadOffsetInBytes = (readOffsetInBytes + offsetInBytes);
newReadOffsetInBytes = (mal_uint32)(readOffsetInBytes + offsetInBytes);
}
}
@@ -345,13 +353,15 @@ mal_result mal_rb_seek_write(mal_rb* pRB, size_t offsetInBytes)
return MAL_INVALID_ARGS;
}
volatile mal_uint32 readOffset = pRB->readOffset;
mal_uint32 readOffsetInBytes;
mal_uint32 readOffsetLoopFlag;
mal_rb__deconstruct_offset(pRB->readOffset, &readOffsetInBytes, &readOffsetLoopFlag);
mal_rb__deconstruct_offset(readOffset, &readOffsetInBytes, &readOffsetLoopFlag);
volatile mal_uint32 writeOffset = pRB->writeOffset;
mal_uint32 writeOffsetInBytes;
mal_uint32 writeOffsetLoopFlag;
mal_rb__deconstruct_offset(pRB->writeOffset, &writeOffsetInBytes, &writeOffsetLoopFlag);
mal_rb__deconstruct_offset(writeOffset, &writeOffsetInBytes, &writeOffsetLoopFlag);
mal_uint32 newWriteOffsetInBytes = writeOffsetInBytes;
mal_uint32 newWriteOffsetLoopFlag = writeOffsetLoopFlag;
@@ -360,16 +370,16 @@ mal_result mal_rb_seek_write(mal_rb* pRB, size_t offsetInBytes)
if (readOffsetLoopFlag == writeOffsetLoopFlag) {
// May end up looping.
if ((writeOffsetInBytes + offsetInBytes) >= pRB->subbufferSizeInBytes) {
newWriteOffsetInBytes = (writeOffsetInBytes + offsetInBytes) - pRB->subbufferSizeInBytes;
newWriteOffsetInBytes = (mal_uint32)(writeOffsetInBytes + offsetInBytes) - pRB->subbufferSizeInBytes;
newWriteOffsetLoopFlag ^= 0x80000000; /* <-- Looped. */
} else {
newWriteOffsetInBytes = (writeOffsetInBytes + offsetInBytes);
newWriteOffsetInBytes = (mal_uint32)(writeOffsetInBytes + offsetInBytes);
}
} else {
if ((writeOffsetInBytes + offsetInBytes) > readOffsetInBytes) {
newWriteOffsetInBytes = readOffsetInBytes;
} else {
newWriteOffsetInBytes = (writeOffsetInBytes + offsetInBytes);
newWriteOffsetInBytes = (mal_uint32)(writeOffsetInBytes + offsetInBytes);
}
}
@@ -383,13 +393,15 @@ mal_int32 mal_rb_pointer_distance(mal_rb* pRB)
return 0;
}
volatile mal_uint32 readOffset = pRB->readOffset;
mal_uint32 readOffsetInBytes;
mal_uint32 readOffsetLoopFlag;
mal_rb__deconstruct_offset(pRB->readOffset, &readOffsetInBytes, &readOffsetLoopFlag);
mal_rb__deconstruct_offset(readOffset, &readOffsetInBytes, &readOffsetLoopFlag);
volatile mal_uint32 writeOffset = pRB->writeOffset;
mal_uint32 writeOffsetInBytes;
mal_uint32 writeOffsetLoopFlag;
mal_rb__deconstruct_offset(pRB->writeOffset, &writeOffsetInBytes, &writeOffsetLoopFlag);
mal_rb__deconstruct_offset(writeOffset, &writeOffsetInBytes, &writeOffsetLoopFlag);
if (readOffsetLoopFlag == writeOffsetLoopFlag) {
return writeOffsetInBytes - readOffsetInBytes;