scheduler_la.h File Reference

Low level scheduling functions for chunk and peer selection. More...

#include "scheduler_common.h"
#include <stdlib.h>

Go to the source code of this file.

Typedefs
typedef int(*	filterFunction )(schedPeerID, schedChunkID)
	Prototype for filter functions that select useful peer-chunk combinations.
typedef double(*	peerEvaluateFunction )(schedPeerID *)
	Prototype for function assigning a weigth to a peer.
typedef double(*	chunkEvaluateFunction )(schedChunkID *)
	Prototype for function assigning a weigth to a given chunk.
typedef double(*	pairEvaluateFunction )(struct PeerChunk *)
	Prototype for function assigning a weigth to a peer-chunk pair.
typedef double(*	double2op )(double, double)
	Prototype for a two operand double function used to combine weights.
Enumerations
enum	SchedOrdering { SCHED_BEST, SCHED_WEIGHTED }
Functions
void	schedSelectPeers (SchedOrdering ordering, schedPeerID *peers, int peers_len, schedChunkID *chunks, int chunks_len, schedPeerID *selected, int *selected_len, filterFunction filter, peerEvaluateFunction peerevaluate)
	Low level scheduler function for selecting peers.
void	schedSelectChunks (SchedOrdering ordering, schedPeerID *peers, int peers_len, schedChunkID *chunks, int chunks_len, schedChunkID *selected, int *selected_len, filterFunction filter, chunkEvaluateFunction chunkevaluate)
	Low level scheduler function for selecting chunks.
void	schedSelectPeerFirst (SchedOrdering ordering, schedPeerID *peers, size_t peers_len, schedChunkID *chunks, size_t chunks_len, struct PeerChunk *selected, size_t *selected_len, filterFunction filter, peerEvaluateFunction peerevaluate, chunkEvaluateFunction chunkevaluate)
	Low level scheduler function for selecting peer-chunk pairs in chunk first order.
void	schedSelectChunkFirst (SchedOrdering ordering, schedPeerID *peers, size_t peers_len, schedChunkID *chunks, size_t chunks_len, struct PeerChunk *selected, size_t *selected_len, filterFunction filter, peerEvaluateFunction peerevaluate, chunkEvaluateFunction chunkevaluate)
	Low level scheduler function for selecting peer-chunk pairs in peer first order.
void	schedSelectComposed (SchedOrdering ordering, schedPeerID *peers, size_t peers_len, schedChunkID *chunks, size_t chunks_len, struct PeerChunk *selected, size_t *selected_len, filterFunction filter, peerEvaluateFunction peerevaluate, chunkEvaluateFunction chunkevaluate, double2op weightcombine)
	Low level scheduler function for selecting peer-chunk pairs based on a composed evaluation function.
void	schedSelectHybrid (SchedOrdering ordering, schedPeerID *peers, size_t peers_len, schedChunkID *chunks, size_t chunks_len, struct PeerChunk *selected, size_t *selected_len, filterFunction filter, pairEvaluateFunction pairevaluate)
	Low level scheduler function for selecting peer-chunk pairs based on a hybrid evaluation function.

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Detailed Description

Low level scheduling functions for chunk and peer selection.

The interface contains highly customizable selector functions. Customization is supported along the following concepts:

1. evaluator functions: selector functions can be parameterized by evaluator functions. By using evaluator functions, the decision process can be decoupled into two parts:
   1. a generic selector function operating on abstract peer and chunk weights
   2. the evaluator function linking the decision process to the peer's knowledge about other peers and chunks
2. selection policy: ChunkFirst, PeerFirst, Composed and Hybrid selection policies are supported
3. ordering method: two kinds of ordering methods are supported:
   1. Best: strict ordering accorging to the given evaluator functions
   2. Weighted: Weighted random selection accorging to the given weight functions
4. filter functions: selections are typically filtered by functions such as whether a given peer (according to local knowledge) needs a given chunk. The abstraction of the filter concept allows for easy modification of these filter conditions.

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Typedef Documentation

typedef double(* chunkEvaluateFunction)(schedChunkID *)

Prototype for function assigning a weigth to a given chunk.

Returns:

the weight associated to the chunk

typedef int(* filterFunction)(schedPeerID,schedChunkID)

Prototype for filter functions that select useful peer-chunk combinations.

Returns:

true if the combination is valid, false otherwise

typedef double(* pairEvaluateFunction)(struct PeerChunk *)

Prototype for function assigning a weigth to a peer-chunk pair.

Returns:

the weight associated to the peer-chunk pair

typedef double(* peerEvaluateFunction)(schedPeerID *)

Prototype for function assigning a weigth to a peer.

Returns:

the weight associated to the peer

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Enumeration Type Documentation

enum SchedOrdering

Scheduler ordering methods

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Function Documentation

void schedSelectChunkFirst	(	SchedOrdering	ordering,
		schedPeerID *	peers,
		size_t	peers_len,
		schedChunkID *	chunks,
		size_t	chunks_len,
		struct PeerChunk *	selected,
		size_t *	selected_len,
		filterFunction	filter,
		peerEvaluateFunction	peerevaluate,
		chunkEvaluateFunction	chunkevaluate
	)

Low level scheduler function for selecting peer-chunk pairs in peer first order.

First a chunk is selected based on weights assigned by the chunkevaluate function. Then, maximum selected_len peers are selected for the given chunk based on weights assigned by the peerevaluate function.

void schedSelectChunks	(	SchedOrdering	ordering,
		schedPeerID *	peers,
		int	peers_len,
		schedChunkID *	chunks,
		int	chunks_len,
		schedChunkID *	selected,
		int *	selected_len,
		filterFunction	filter,
		chunkEvaluateFunction	chunkevaluate
	)

Low level scheduler function for selecting chunks.

If called with peers_len=0, it will not consider peers in the selection. Otherwise, if peers_len>0, only those chunks will be selected that could be interesting for at least one of the given peers.

void schedSelectComposed	(	SchedOrdering	ordering,
		schedPeerID *	peers,
		size_t	peers_len,
		schedChunkID *	chunks,
		size_t	chunks_len,
		struct PeerChunk *	selected,
		size_t *	selected_len,
		filterFunction	filter,
		peerEvaluateFunction	peerevaluate,
		chunkEvaluateFunction	chunkevaluate,
		double2op	weightcombine
	)

Low level scheduler function for selecting peer-chunk pairs based on a composed evaluation function.

A maximum of selected_len peer-chunk pairs are selected based on a composed weight function.

Parameters:

[in]	chunkevaluate	function to assign a weight to each chunk
[in]	peerevaluate	function to assign a weight to each peer
[in]	weightcombine	operation to combine peer and chunk weight into one weight

void schedSelectHybrid	(	SchedOrdering	ordering,
		schedPeerID *	peers,
		size_t	peers_len,
		schedChunkID *	chunks,
		size_t	chunks_len,
		struct PeerChunk *	selected,
		size_t *	selected_len,
		filterFunction	filter,
		pairEvaluateFunction	pairevaluate
	)

Low level scheduler function for selecting peer-chunk pairs based on a hybrid evaluation function.

A maximum of selected_len peer-chunk pairs are selected based on the given evaluation function.

Parameters:

[in]

pairevaluate

function to assign a weight to each peer-chunk pair

void schedSelectPeerFirst	(	SchedOrdering	ordering,
		schedPeerID *	peers,
		size_t	peers_len,
		schedChunkID *	chunks,
		size_t	chunks_len,
		struct PeerChunk *	selected,
		size_t *	selected_len,
		filterFunction	filter,
		peerEvaluateFunction	peerevaluate,
		chunkEvaluateFunction	chunkevaluate
	)

Low level scheduler function for selecting peer-chunk pairs in chunk first order.

First a peer is selected based on weights assigned by the peerevaluate function. Then, maximum selected_len chunks are selected for the given peer based on weights assigned by the chunkevaluate function.

void schedSelectPeers	(	SchedOrdering	ordering,
		schedPeerID *	peers,
		int	peers_len,
		schedChunkID *	chunks,
		int	chunks_len,
		schedPeerID *	selected,
		int *	selected_len,
		filterFunction	filter,
		peerEvaluateFunction	peerevaluate
	)

Low level scheduler function for selecting peers.

If called with chunks_len=0, it will not consider chunks in the selection. Otherwise, if chunks_len>0, only those peers will be selected that could be interesting for at least one of the given chunks.

Parameters:

[in]	ordering	the ordering method to be used
[in]	peers	list of peers to select from
[in]	peers_len	length of peers list
[in]	chunk	list of chunks to select from
[in]	chunks_len	length of chunks list
[out]	selected	list of peers selected by the function
[in,out]	selected_len	in: maximum number of peers to select; out: number of peers selected
[in]	filter	only peers that satisfy the filter condition can be selected
[in]	peerevaluate	peers are selected based on the weight assigned by this evaluator function