114 lines
2.2 KiB
C++
114 lines
2.2 KiB
C++
/*++
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Copyright (c) 1996 Microsoft Corporation
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Module Name:
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callid.cxx
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Abstract:
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Implements a cache of callids used for running down OIDs
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This is almost twice as fast as UuidCreate() but that doesn't
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mean much. UuidCreate takes 3 microseconds, this 1.4 (hit) or
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4.2 (miss) on a P90.
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This codes real advantage would be on MP machines. But it is
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not performance critical and is probably overkill.
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Author:
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Mario Goertzel [MarioGo]
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Revision History:
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MarioGo 1/18/1996 Bits 'n pieces
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--*/
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#include <or.hxx>
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enum CacheState { CallidEmpty = 0,
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CallidAllocated = 1,
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CallidFree = -1 };
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struct CacheElement
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{
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CacheState _state;
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UUID _callid;
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};
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CacheElement CallidCache[4] = { CallidEmpty, {0},
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CallidEmpty, {0},
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CallidEmpty, {0},
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CallidEmpty, {0} };
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INT
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AllocateCallId(
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OUT UUID &Callid
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)
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{
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INT i;
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LONG l;
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RPC_STATUS status;
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for (i = 0; i < 4; i++)
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{
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if (CallidCache[i]._state != CallidAllocated)
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{
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l = InterlockedExchange((PLONG)&CallidCache[i]._state, CallidAllocated);
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switch(l)
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{
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case CallidAllocated:
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continue;
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case CallidFree:
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Callid = CallidCache[i]._callid;
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return(i);
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case CallidEmpty:
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status = UuidCreate(&Callid);
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VALIDATE((status, RPC_S_UUID_LOCAL_ONLY, RPC_S_OK, 0));
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CallidCache[i]._callid = Callid;
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return(i);
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}
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}
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}
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status = UuidCreate(&Callid);
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VALIDATE((status, RPC_S_UUID_LOCAL_ONLY, RPC_S_OK, 0));
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return(-1);
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}
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void
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FreeCallId(
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IN INT hint
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)
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/*++
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Routine Description:
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Frees a callid previously allcoated with AllocateCallId().
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Arguments:
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hint - The hint value returned by the previous call to AllocateCallId().
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Return Value:
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None
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--*/
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{
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ASSERT((hint > -2) && (hint < 4));
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if (hint >= 0)
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{
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CallidCache[hint]._state = CallidFree;;
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}
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}
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