Shared Persistent Heap, single producer single consumer queue. For shared memory multi-thread/multi-core applications. This implementation uses atomic operations to implement Lock Free Producer/Consumer queues (SPHSinglePCQueue_t). More...

#include "sastype.h"
#include "sphlfentry.h"

Macros
#define	__C__
	ignore this macro behind the curtain

#define	SPHSPCQUEUE_CIRCULAR (1)
	internal options flag for circular log buffers

#define	SPHSPCQUEUE_CIRCULAR_WRAPED (1<<1)
	internal options flag set when circular log buffers have wrapped

#define	SPHSPCQUEUE_CIRCULAR_NOTFIRST (1<<2)
	internal options flag set when circular log buffers have wrapped multiple times

#define	SPHSPCQUEUE_CACHE_PREFETCH0 (1<<3)
	internal options flag for prefetching the immediate (0 offset) cache-line

#define	SPHSPCQUEUE_CACHE_PREFETCH1 (1<<4)
	internal options flag for prefetching the next (line size offset) cache-line

#define	SPHSPCQUEUE_CIRCULAR_RESETMASK
	internal options mask flag used the reset circular log buffers More...

Typedefs
typedef void *	SPHSinglePCQueue_t
	Handle to an instance of SPH Lock Free Single Producer, Single Consumer Queue. More...

Functions
__C__ SPHSinglePCQueue_t	SPHSinglePCQueueInit (void *buf_seg, block_size_t buf_size)
	Initialize a shared storage block as a Lock Free PC Queue. More...

__C__ SPHSinglePCQueue_t	SPHSinglePCQueueInitWithStride (void *buf_seg, block_size_t buf_size, unsigned short entry_stride, unsigned int options)
	Initialize a shared storage block as a Lock Free Single Producer Single Consumer Queue with a fixed entry stride. More...

__C__ SPHSinglePCQueue_t	SPHSinglePCQueueCreate (block_size_t buf_size)
	Allocate and initialize a shared storage block as a Lock Free Single Producer Single Consumer Queue. More...

__C__ SPHSinglePCQueue_t	SPHSinglePCQueueCreateWithStride (block_size_t buf_size, unsigned short stride)
	Allocate and initialize a shared storage block as a Lock Free Single Producer Single Consumer Queue. More...

__C__ int	SPHSinglePCQueueGetStride (SPHSinglePCQueue_t queue)
	Return the entry stride for an existing Lock Free Single Producer Single Consumer Queue. More...

__C__ void *	SPHSinglePCQueueAllocRaw (SPHSinglePCQueue_t queue)
	Allows the Producer thread to return the address of a (raw) queue entry allocated from the specified Single Producer Single Consumer Queue. More...

__C__ SPHLFEntryHandle_t *	SPHSinglePCQueueAllocStrideEntry (SPHSinglePCQueue_t queue, int catcode, int subcode, SPHLFEntryHandle_t *handlespace)
	Allows the producer thread to allocate and initialize the header of a queue entry for access. The allocation is from the specified Single Producer Single Consumer Queue. More...

__C__ SPHLFEntryHandle_t *	SPHSinglePCQueueAllocStrideTimeStamped (SPHSinglePCQueue_t queue, int catcode, int subcode, SPHLFEntryHandle_t *handlespace)
	Allows the producer thread to allocate and initialize the header, of a queue entry for access. The allocation is from the specified Single Producer Single Consumer Queue. More...

__C__ int	SPHSinglePCQueueEntryComplete (SPHLFEntryHandle_t *entryhandle)
	Allows the producer thread to mark the queue entry, specified by the entry handle, as complete. This makes the queue entry accessible to the consumer thread. More...

__C__ int	SPHSinglePCQueueEntryIsComplete (SPHLFEntryHandle_t *entryhandle)
	Return the status of the entry specified by the entry handle. More...

__C__ SPHLFEntryHandle_t *	SPHSinglePCQueueGetNextComplete (SPHSinglePCQueue_t queue, SPHLFEntryHandle_t *handlespace)
	Allows the consumer to get the next completed queue entry from the specified single producer single consumer queue. More...

__C__ int	SPHSinglePCQueueFreeNextEntry (SPHSinglePCQueue_t queue)
	Allows the consumer to free the queue entry it just processed (using SPHSinglePCQueueGetNextComplete), from the specified single producer single consumer queue. More...

__C__ int	SPHSinglePCQueueEmpty (SPHSinglePCQueue_t queue)
	Return the status of the specified queue. More...

__C__ block_size_t	SPHSinglePCQueueFreeSpace (SPHSinglePCQueue_t queue)
	Returns the amount of free space (in bytes) remaining in the specified queue. More...

__C__ int	SPHSinglePCQueueFull (SPHSinglePCQueue_t queue)
	Return the status of the specified queue. More...

__C__ int	SPHSinglePCQueueResetAsync (SPHSinglePCQueue_t queue)
	Resets the specific queue to empty state asynchronously (without locking or atomic updates). More...

__C__ int	SPHSinglePCQueuePrefetch (SPHSinglePCQueue_t queue)
	Prefetch pages from the specific queue. More...

__C__ int	SPHSinglePCQueueSetCachePrefetch (SPHSinglePCQueue_t queue, int prefetch)
	Set the cache-line prefetch options for entry allocate. More...

__C__ int	SPHSinglePCQueueDestroy (SPHSinglePCQueue_t queue)
	Destroys the queue and frees the SAS storage for reuse. More...

Detailed Description

Shared Persistent Heap, single producer single consumer queue. For shared memory multi-thread/multi-core applications. This implementation uses atomic operations to implement Lock Free Producer/Consumer queues (SPHSinglePCQueue_t).

! This API supports atomic allocation of storage for queue entries for zero copy persistence and sharing. Zero copy queues divides the process of producing a queue entry in to three steps:

Allocate the queue entry (and initialize the header)
Use the return entry handle to fill in application specific data.
Marks the entry complete in the header.

#include <sphlfentry.h>
SPHLFEntryHandle_t *handle, handle0;
typedef struct data_struct11 {
        double  field0;
        int             field1;
        int             field2;
        void    *field3;
        } data_struct11;
        // Allocate zero copy queue entry
        handle = SPHSinglePCQueueAllocStrideEntry (pcqueue, CAT_CODE, SUBCAT_CODE, &handle0);
        if (handle)
        {       // insert data into the allocated queue entry
                data_struct11 *struct_ptr;
                if (SPHLFEntryAddPtr (handle, (void*) sas_data_buff)
                {
                        printf("error  SPHLFEntryAddPtr(%p, sas_data_buff) failed)\n",
                                   handle);
                }
                if (SPHLFEntryAddInt (handle, data_int1))
                {
                        printf("error  SPHLFEntryAddInt(%p, data_int1) failed)\n",
                                   handle);
                }
                if (SPHLFEntryAddString (handle, (char*)data_string1))
                {
                        printf("error  SPHLFEntryAddString(%p, data_string1) failed)\n",
                                   handle);
                }
                struct_ptr  = (data_struct11*)SPHENTRYALLOCSTRUCT (handle, data_struct11);
                if (struct_ptr)
                {       // store struct fields directly into allocated queue entry
                        struct_ptr->field0 = data_double1;
                        struct_ptr->field1 = data_int2;
                        struct_ptr->field2 = data_int3;
                        struct_ptr->field3 = (void*)sas_data_buff2;
                } else {
                        printf("error  SPHENTRYALLOCSTRUCT(%p, data_struct11) failed)\n",
                                   handle);
                }
                // Mark the entry complete and available to the consumer
                SPHSinglePCQueueEntryComplete(handle)
        } else {
                while (SPHSinglePCQueueFull(pcqueue))
                {
                        // pacing code
                }
        }

The consumer can access queue entries once they are marked complete. The consumer:

checks (spins) for the next allocated entry to become complete.
uses the returned entry handle to directly access the entry contents.
When done processing the queue entry, it marks the entry header invalid and deallocates the entry.
This makes the next queue entry available, if any.

#include <sphlfentry.h>
SPHLFEntryHandle_t *handle, handle0;
typedef struct data_struct11 {
        double  field0;
        int             field1;
        int             field2;
        void    *field3;
        } data_struct11;
        // Get next queue entry
        handle = SPHSinglePCQueueGetNextComplete (pcqueue, &handle0);
        if (handle)
        {       // insert data into the allocated queue entry
                data_struct11 *struct_ptr;
                sas_data_buff = SPHLFEntryGetNextPtr (handle);
                if (!sas_data_buff)
                {
                        printf("error  SPHLFEntryAddPtr(%p, sas_data_buff) failed)\n",
                                   handle);
                }
                data_int1 = SPHLFEntryGetNextInt (handle);
                data_string1 = SPHLFEntryGetNextString (handle);
                if (data_string1)
                {
                        printf("error  SPHLFEntryGetNextString(%p, data_string1) failed)\n",
                                   handle);
                }
                struct_ptr  = (data_struct11*)SPHENTRYALLOCSTRUCT (handle, data_struct11);
                if (struct_ptr)
                {       // access struct fields directly from queue entry
                        data_double1    = struct_ptr->field0;
                        data_int2               = struct_ptr->field1;
                        data_int3               = struct_ptr->field2;
                        sas_data_buff2  = struct_ptr->field3;
                } else {
                        printf("error  SPHENTRYALLOCSTRUCT(%p, data_struct11) failed)\n",
                                   handle);
                }
                // Mark the entry free and available for reuse
                SPHSinglePCQueueFreeNextEntry(pcqueue)
        } else {
                while (SPHSinglePCQueueEmpty(pcqueue))
                {
                        // pacing code
                }
        }

In this implementation the allocation of the entry is minimally serialized based on the assumption that only one (producer) thread will be allocating queue entries. Likewise the assumption is that there is only one consumer thread per SPHSinglePCQueue_t instance. This allows independent producer/consumer thread pairs to interact with a queue instance with minimum synchronization and overhead.

As an option the queue entry allocator will fill in a 4 or 16 byte entry header with:

Entry status and length.
Entry identifying Category and SubCategory codes.
Process and Thread Ids.
High resolution timestamp.

Any additional storage allocated to the entry (after the header) is available for application specific data. This API also provides several mechanisms to store application data including; direct array or structure overlay, and a streams like mechanism. The API provides a completion function (SPHSinglePCQueueEntryComplete) which provides any memory barriers required by the platform and marks the entry complete.

The API support simple circular queues and requires a constant entry stride. A stride that matches or is multiple of the cache line size can improve performance by avoiding "false sharing" of cache lines containing multiple queue entries across cores/sockets.

Todo:: Additional work will include automatic pacing with Hysteresis

Macro Definition Documentation

#define SPHSPCQUEUE_CIRCULAR_RESETMASK

Value:

(SPHSPCQUEUE_CIRCULAR | \
		SPHSPCQUEUE_CACHE_PREFETCH0 | \
		SPHSPCQUEUE_CACHE_PREFETCH1)

internal options mask flag used the reset circular log buffers

Typedef Documentation

typedef void* SPHSinglePCQueue_t

Handle to an instance of SPH Lock Free Single Producer, Single Consumer Queue.

The type is SAS_RUNTIME_PCQUEUE

Function Documentation

__C__ void* SPHSinglePCQueueAllocRaw ( SPHSinglePCQueue_t queue )

Allows the Producer thread to return the address of a (raw) queue entry allocated from the specified Single Producer Single Consumer Queue.

The allocation size is rounded up to the next quadword boundary. Mostly for internal use and testing. If the specified queue is full the allocation may fail.

Warning: This function is primarily for internal testing and should not be used by applications.

Parameters

queue Handle of a producer consumer queue.

Returns: address of the raw entry, or 0 (NULL) if the allocation failed. For example the Allocate may fail if the queue is full.

__C__ SPHLFEntryHandle_t* SPHSinglePCQueueAllocStrideEntry	(	SPHSinglePCQueue_t	queue,
		int	catcode,
		int	subcode,
		SPHLFEntryHandle_t *	handlespace
	)

Allows the producer thread to allocate and initialize the header of a queue entry for access. The allocation is from the specified Single Producer Single Consumer Queue.

The allocation size is the stride set when the PC queue was initialized/created. The Entry status, Category, Subcategory, and length are stored in the header of the new entry. Returns an entry handle which allows the application to insert application specific data into the entry via the sphlfentry.h API. If the specified queue is full the allocation may fail.

Note: The queue entry is not ready for access by the Consumer thread, until additional application data is inserted and the entry is completed (via SPHSinglePCQueueEntryComplete).

Parameters

queue	Handle of a producer consumer queue.
catcode	Category code to the new entry.
subcode	Subcategory code to the new entry.
handlespace	Address of local area that will be initialized as a SPHLFEntryHandle_t for the allocated entry.

Returns: Handle of the initialized queue entry handle, from the handlespace parm, or 0 (NULL) if the allocation failed. For example the Allocate may fail if the queue is full.

__C__ SPHLFEntryHandle_t* SPHSinglePCQueueAllocStrideTimeStamped	(	SPHSinglePCQueue_t	queue,
		int	catcode,
		int	subcode,
		SPHLFEntryHandle_t *	handlespace
	)

Allows the producer thread to allocate and initialize the header, of a queue entry for access. The allocation is from the specified Single Producer Single Consumer Queue.

The allocation size is the stride set when the PC queue was initialized/created. The Category, Subcategory, PID, TID and high precision timestamp are stored in the header of the new entry. Returns an entry handle which allows the application to insert application specific data into the entry via the sphlflogentry.h API. If the specified queue is full the allocation may fail.

Note: The queue entry is not ready for access by the Consumer thread, until additional application data is inserted and the entry is completed (via SPHSinglePCQueueEntryComplete).

Parameters

queue	Handle of a producer consumer queue.
catcode	Category code to the new entry.
subcode	subcategory code to the new entry.
handlespace	Address of local area that will be initialized as a SPHLFEntryHandle_t for the allocated entry.

Returns: Handle of the initialized logger entry, from the handlespace parm, or 0 (NULL) if the allocation failed. For example the Allocate may fail if the queue is full.

__C__ SPHSinglePCQueue_t SPHSinglePCQueueCreate ( block_size_t buf_size )

Allocate and initialize a shared storage block as a Lock Free Single Producer Single Consumer Queue.

Allocate a block from SAS storage and initialize that block block as a PC Queue. The storage block must be power of two in size.

Parameters

buf_size power of two size of the heap to be initialized.

Returns: a handle to the initialized SPHSinglePCQueue_t.

__C__ SPHSinglePCQueue_t SPHSinglePCQueueCreateWithStride	(	block_size_t	buf_size,
		unsigned short	stride
	)

Allocate and initialize a shared storage block as a Lock Free Single Producer Single Consumer Queue.

Allocate a block from SAS storage and initialize that block block as a Logger. The storage block must be power of two in size.

Parameters

buf_size	power of two size of the heap to be initialized.
stride	the stride offset is bytes between allocated entries.

Returns: a handle to the initialized SPHSinglePCQueue_t.

__C__ int SPHSinglePCQueueDestroy ( SPHSinglePCQueue_t queue )

Destroys the queue and frees the SAS storage for reuse.

Parameters

queue Handle to a queue to be destroyed.

Returns: 0 if successful.

__C__ int SPHSinglePCQueueEmpty ( SPHSinglePCQueue_t queue )

Return the status of the specified queue.

Parameters

queue Handle to a queue.

Returns: true if the queue is currently Empty (no entries). Otherwise False.

__C__ int SPHSinglePCQueueEntryComplete ( SPHLFEntryHandle_t * entryhandle )

Allows the producer thread to mark the queue entry, specified by the entry handle, as complete. This makes the queue entry accessible to the consumer thread.

Also executes any memory barriers required by the platform to ensure that all previous stores to this entry by this thread are visible to other threads.

Warning: The Producer thread should not touch or modify a queue entry after calling EntryComplete. This is important to both correctness and performance.

Parameters

entryhandle log entry Handle for an allocated entry.

Returns: 0 if successful.

__C__ int SPHSinglePCQueueEntryIsComplete ( SPHLFEntryHandle_t * entryhandle )

Return the status of the entry specified by the entry handle.

Parameters

entryhandle log entry Handle for an allocated entry.

Returns: true if the entry was complete (SPHSinglePCQueueEntryComplete has been called for this entry). Otherwise False.

__C__ int SPHSinglePCQueueFreeNextEntry ( SPHSinglePCQueue_t queue )

Allows the consumer to free the queue entry it just processed (using SPHSinglePCQueueGetNextComplete), from the specified single producer single consumer queue.

Mark the current queue tail entry as free (unallocated and invalid) and bump the queue tail pointer to the next entry. If the specified queue is empty or the current tail entry is not yet completed the Free may fail.

Warning: The Consumer thread should not touch or modify a queue entry after calling FreeEntry. This is important to both correctness and performance.

Parameters

queue Handle of a producer consumer queue.

Returns: True for successful tail free, otherwise indicated failure. For example the Get may fail if the queue is empty or the next tail entry is not yet completed.

__C__ block_size_t SPHSinglePCQueueFreeSpace ( SPHSinglePCQueue_t queue )

Returns the amount of free space (in bytes) remaining in the specified queue.

Parameters

queue Handle to a queue.

Returns: number of bytes of free space remaining in the queue buffer.

__C__ int SPHSinglePCQueueFull ( SPHSinglePCQueue_t queue )

Return the status of the specified queue.

Parameters

queue Handle to a queue.

Returns: true if the queue is currently full. Otherwise False.

__C__ SPHLFEntryHandle_t* SPHSinglePCQueueGetNextComplete	(	SPHSinglePCQueue_t	queue,
		SPHLFEntryHandle_t *	handlespace
	)

Allows the consumer to get the next completed queue entry from the specified single producer single consumer queue.

Returns an entry handle which allows the application to access the application specific data inserted by the produced thread. If the specified queue is empty or the next queue is not yet completed the get may fail.

Parameters

queue	Handle of a producer consumer queue.
handlespace	Address of local area that will be initialized as a SPHLFEntryHandle_t for the allocated entry.

Returns: Handle of the initialized logger entry, from the handlespace parm, or 0 (NULL) if the get failed. For example the Get may fail if the queue is empty or the next tail entry is not yet completed.

__C__ int SPHSinglePCQueueGetStride ( SPHSinglePCQueue_t queue )

Return the entry stride for an existing Lock Free Single Producer Single Consumer Queue.

Parameters

queue Handle of a producer consumer queue.

Returns: the entry stride of strided queues, 0 if not strided, or -1 is not a valid SPHSinglePCQueue_t.

__C__ SPHSinglePCQueue_t SPHSinglePCQueueInit	(	void *	buf_seg,
		block_size_t	buf_size
	)

Initialize a shared storage block as a Lock Free PC Queue.

Initialize the specified storage block as Lock Free PC Queue control blocks. The storage block must be power of two in size and have the same power of two (or better) alignment. The type should be SAS_RUNTIME_PCQUEUE.

Parameters

buf_seg	a block of allocated SAS storage matching the buf_size.
buf_size	power of two size of the heap to be initialized.

Returns: a handle to the initialized SPHSinglePCQueue_t.

__C__ SPHSinglePCQueue_t SPHSinglePCQueueInitWithStride	(	void *	buf_seg,
		block_size_t	buf_size,
		unsigned short	entry_stride,
		unsigned int	options
	)

Initialize a shared storage block as a Lock Free Single Producer Single Consumer Queue with a fixed entry stride.

Initialize the specified storage block as Lock Free PC Queue control blocks. The stride and control flags are also stored. The storage block must be power of two in size and have the same power of two (or better) alignment. The type should be SAS_RUNTIME_PCQUEUE.

Parameters

buf_seg	a block of allocated SAS storage matching the buf_size.
buf_size	power of two size of the heap to be initialized.
entry_stride	the stride offset is bytes between allocated entries.
options	option bits.

Returns: a handle to the initialized SPHSinglePCQueue_t.

__C__ int SPHSinglePCQueuePrefetch ( SPHSinglePCQueue_t queue )

Prefetch pages from the specific queue.

Parameters

queue Handle to a queue.

Returns: 0 if successful.

__C__ int SPHSinglePCQueueResetAsync ( SPHSinglePCQueue_t queue )

Resets the specific queue to empty state asynchronously (without locking or atomic updates).

Internal use for testing.

Parameters

queue Handle to a queue.

Returns: 0 if successful.

__C__ int SPHSinglePCQueueSetCachePrefetch	(	SPHSinglePCQueue_t	queue,
		int	prefetch
	)

Set the cache-line prefetch options for entry allocate.

prefetch == 0; No prefetch issued.
prefetch == 1; Prefetch the currently allocated cache-line.
prefetch == 2; Prefetch the cache-line following the allocated entry.
prefetch == 3; Prefetch the current and next cache-lines.

@param queue Handle to a queue.
@param prefetch prefetch option code.
@return 0 if successful.

Macros

Typedefs

Functions

Detailed Description

Macro Definition Documentation

Typedef Documentation

Function Documentation