mirror of http://192.168.1.51:8099/lmh188/twain3.0
190 lines
3.9 KiB
C
190 lines
3.9 KiB
C
/*++
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Copyright (c) 1989 Microsoft Corporation
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Module Name:
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backpack.h
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Abstract:
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This module contains the package for pseudo polling. When a caller
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requests the same operation and gets the same error return the rdr
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must prevent flooding the network by backing off requests. Examples
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of when this is desirable are receiving 0 bytes on consequtive reads
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and consequtive fails on a file lock.
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If the caller is flooding the network, the rdr will return the 0 bytes
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or lock fail to the user until NextTime. When NextTime is reached
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the network will be used.
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Author:
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Revision History:
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--*/
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#ifndef _BACKPACK_
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#define _BACKPACK_
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typedef struct _THROTTLING_STATE {
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LARGE_INTEGER NextTime; // Do not access the network until
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// CurrentTime >= NextTime
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__volatile ULONG CurrentIncrement; // Number of Increments applied to calculate NextTime
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ULONG MaximumDelay; // Specifies slowest rate that we will back off to
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// NextTime <= CurrentTime + (Interval * MaximumDelay)
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LARGE_INTEGER Increment;// {0,10000000} == 1 second
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__volatile ULONG NumberOfQueries;
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} THROTTLING_STATE, *PTHROTTLING_STATE;
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//++
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//
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// VOID
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// RxInitializeThrottlingState(
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// IN PTHROTTLING_STATE pBP,
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// IN ULONG Increment,
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// IN ULONG MaximumDelay
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// );
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//
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// Routine Description:
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//
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// This routine is called to initialize the back off structure (usually in
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// an Icb).
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//
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// Arguments:
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//
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// pBP - Supplies back pack data for this request.
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// Increment - Supplies the increase in delay in milliseconds, each time a request
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// to the network fails.
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// MaximumDelay- Supplies the longest delay the backoff package can introduce
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// in milliseconds.
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//
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// Return Value:
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//
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// None.
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//
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//--
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#define RxInitializeThrottlingState( _pBP, _Increment, _MaximumDelay ) { \
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if ((_Increment)>0) { \
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(_pBP)->Increment.QuadPart = (_Increment) * 10000; \
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(_pBP)->MaximumDelay = (_MaximumDelay) / (_Increment); \
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(_pBP)->CurrentIncrement = 0; \
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}}
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//++
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//
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// VOID
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// RxUninitializeBackPack(
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// IN PTHROTTLING_STATE pBP
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// )
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//
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// Routine Description:
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//
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// Resets the Back Pack specified. Currently no work needed.
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//
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// Arguments:
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//
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// pBP - Supplies back pack address.
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//
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// Return Value:
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//
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// None.
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//
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//--
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#define RxUninitializeBackPack( pBP ) ()
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// RxShouldRequestBeThrottled indicates when the request should not go to the network.
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BOOLEAN
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RxShouldRequestBeThrottled(
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IN PTHROTTLING_STATE pBP
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);
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// Register the last request as failed.
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VOID
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RxInitiateOrContinueThrottling (
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IN PTHROTTLING_STATE pBP
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);
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// Register the last request as worked.
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//++
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//
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// VOID
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// RxTerminateThrottling(
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// IN PTHROTTLING_STATE pBP
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// )
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//
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// Routine Description:
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//
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// Sets the Delay to zero. This routine is called each time that
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// a network request succeeds to avoid the next request backing off.
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//
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// Arguments:
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//
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// pBP - Supplies back pack address.
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//
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// Return Value:
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//
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// None.
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//
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//--
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#define RxTerminateThrottling( pBP ) ( (pBP)->CurrentIncrement = 0 )
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//++
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//
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// VOID
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// RxInitializeBackoffPackage (
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// VOID
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// )
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//
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// Routine Description:
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//
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// This routine initializes the redirector back off package.
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//
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// Arguments:
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//
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// None
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//
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// Return Value:
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//
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// None.
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//
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//--
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#define RxInitializeBackoffPackage( )
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//++
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//
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// VOID
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// RxUninitializeBackoffPackage (
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// VOID
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// )
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//
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// Routine Description:
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//
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// This routine uninitializes the redirector back off package.
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//
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// Arguments:
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//
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// None
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//
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// Return Value:
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//
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// None.
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//
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//--
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#define RxUninitializeBackoffPackage( )
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#endif /* _BACKPACK_ */
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