d87691ec60
git-subtree-dir: subtree/rabit git-subtree-split: c7282acb2a92e1d6a32614889ff466fec58937f3
257 lines
10 KiB
C++
257 lines
10 KiB
C++
/*!
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* Copyright (c) 2014 by Contributors
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* \file engine.h
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* \brief This file defines the core interface of rabit library
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* \author Tianqi Chen, Nacho, Tianyi
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*/
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#ifndef RABIT_ENGINE_H_
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#define RABIT_ENGINE_H_
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#include <string>
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#include "../rabit_serializable.h"
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namespace MPI {
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/*! \brief MPI data type just to be compatible with MPI reduce function*/
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class Datatype;
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}
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/*! \brief namespace of rabit */
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namespace rabit {
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/*! \brief core interface of the engine */
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namespace engine {
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/*! \brief interface of core Allreduce engine */
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class IEngine {
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public:
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/*!
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* \brief Preprocessing function, that is called before AllReduce,
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* used to prepare the data used by AllReduce
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* \param arg additional possible argument used to invoke the preprocessor
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*/
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typedef void (PreprocFunction) (void *arg);
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/*!
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* \brief reduce function, the same form of MPI reduce function is used,
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* to be compatible with MPI interface
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* In all the functions, the memory is ensured to aligned to 64-bit
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* which means it is OK to cast src,dst to double* int* etc
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* \param src pointer to source space
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* \param dst pointer to destination reduction
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* \param count total number of elements to be reduced (note this is total number of elements instead of bytes)
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* the definition of the reduce function should be type aware
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* \param dtype the data type object, to be compatible with MPI reduce
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*/
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typedef void (ReduceFunction) (const void *src,
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void *dst, int count,
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const MPI::Datatype &dtype);
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/*!
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* \brief performs in-place Allreduce, on sendrecvbuf
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* this function is NOT thread-safe
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* \param sendrecvbuf_ buffer for both sending and receiving data
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* \param type_nbytes the number of bytes the type has
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* \param count number of elements to be reduced
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* \param reducer reduce function
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* \param prepare_func Lazy preprocessing function, if it is not NULL, prepare_fun(prepare_arg)
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* will be called by the function before performing Allreduce in order to initialize the data in sendrecvbuf.
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* If the result of Allreduce can be recovered directly, then prepare_func will NOT be called
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* \param prepare_arg argument used to pass into the lazy preprocessing function
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*/
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virtual void Allreduce(void *sendrecvbuf_,
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size_t type_nbytes,
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size_t count,
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ReduceFunction reducer,
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PreprocFunction prepare_fun = NULL,
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void *prepare_arg = NULL) = 0;
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/*!
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* \brief broadcasts data from root to every other node
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* \param sendrecvbuf_ buffer for both sending and receiving data
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* \param size the size of the data to be broadcasted
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* \param root the root worker id to broadcast the data
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*/
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virtual void Broadcast(void *sendrecvbuf_, size_t size, int root) = 0;
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/*!
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* \brief explicitly re-initialize everything before calling LoadCheckPoint
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* call this function when IEngine throws an exception,
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* this function should only be used for test purposes
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*/
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virtual void InitAfterException(void) = 0;
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/*!
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* \brief loads the latest check point
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* \param global_model pointer to the globally shared model/state
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* when calling this function, the caller needs to guarantee that the global_model
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* is the same in all nodes
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* \param local_model pointer to the local model that is specific to current node/rank
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* this can be NULL when no local model is needed
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*
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* \return the version number of the model loaded
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* if returned version == 0, this means no model has been CheckPointed
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* the p_model is not touched, users should do necessary initialization by themselves
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*
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* Common usage example:
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* int iter = rabit::LoadCheckPoint(&model);
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* if (iter == 0) model.InitParameters();
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* for (i = iter; i < max_iter; ++i) {
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* do many things, include allreduce
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* rabit::CheckPoint(model);
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* }
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*
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* \sa CheckPoint, VersionNumber
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*/
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virtual int LoadCheckPoint(ISerializable *global_model,
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ISerializable *local_model = NULL) = 0;
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/*!
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* \brief checkpoints the model, meaning a stage of execution was finished
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* every time we call check point, a version number increases by ones
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*
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* \param global_model pointer to the globally shared model/state
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* when calling this function, the caller needs to guarantee that the global_model
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* is the same in every node
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* \param local_model pointer to the local model that is specific to current node/rank
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* this can be NULL when no local state is needed
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*
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* NOTE: local_model requires explicit replication of the model for fault-tolerance, which will
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* bring replication cost in CheckPoint function. global_model does not need explicit replication.
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* So, only CheckPoint with global_model if possible
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*
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* \sa LoadCheckPoint, VersionNumber
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*/
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virtual void CheckPoint(const ISerializable *global_model,
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const ISerializable *local_model = NULL) = 0;
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/*!
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* \brief This function can be used to replace CheckPoint for global_model only,
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* when certain condition is met (see detailed explanation).
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*
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* This is a "lazy" checkpoint such that only the pointer to global_model is
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* remembered and no memory copy is taken. To use this function, the user MUST ensure that:
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* The global_model must remain unchanged until the last call of Allreduce/Broadcast in the current version finishes.
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* In other words, global_model can be changed only between the last call of
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* Allreduce/Broadcast and LazyCheckPoint in the current version
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*
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* For example, suppose the calling sequence is:
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* LazyCheckPoint, code1, Allreduce, code2, Broadcast, code3, LazyCheckPoint
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*
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* If the user can only change global_model in code3, then LazyCheckPoint can be used to
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* improve the efficiency of the program.
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* \param global_model pointer to the globally shared model/state
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* when calling this function, the caller needs to guarantee that global_model
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* is the same in every node
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* \sa LoadCheckPoint, CheckPoint, VersionNumber
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*/
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virtual void LazyCheckPoint(const ISerializable *global_model) = 0;
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/*!
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* \return version number of the current stored model,
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* which means how many calls to CheckPoint we made so far
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* \sa LoadCheckPoint, CheckPoint
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*/
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virtual int VersionNumber(void) const = 0;
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/*! \brief gets rank of current node */
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virtual int GetRank(void) const = 0;
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/*! \brief gets total number of nodes */
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virtual int GetWorldSize(void) const = 0;
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/*! \brief gets the host name of the current node */
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virtual std::string GetHost(void) const = 0;
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/*!
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* \brief prints the msg in the tracker,
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* this function can be used to communicate progress information to
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* the user who monitors the tracker
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* \param msg message to be printed in the tracker
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*/
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virtual void TrackerPrint(const std::string &msg) = 0;
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};
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/*! \brief initializes the engine module */
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void Init(int argc, char *argv[]);
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/*! \brief finalizes the engine module */
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void Finalize(void);
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/*! \brief singleton method to get engine */
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IEngine *GetEngine(void);
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/*! \brief namespace that contains stubs to be compatible with MPI */
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namespace mpi {
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/*!\brief enum of all operators */
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enum OpType {
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kMax = 0,
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kMin = 1,
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kSum = 2,
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kBitwiseOR = 3
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};
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/*!\brief enum of supported data types */
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enum DataType {
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kChar = 0,
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kUChar = 1,
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kInt = 2,
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kUInt = 3,
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kLong = 4,
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kULong = 5,
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kFloat = 6,
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kDouble = 7
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};
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} // namespace mpi
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/*!
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* \brief perform in-place Allreduce, on sendrecvbuf
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* this is an internal function used by rabit to be able to compile with MPI
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* do not use this function directly
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* \param sendrecvbuf buffer for both sending and receiving data
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* \param type_nbytes the number of bytes the type has
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* \param count number of elements to be reduced
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* \param reducer reduce function
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* \param dtype the data type
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* \param op the reduce operator type
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* \param prepare_func Lazy preprocessing function, lazy prepare_fun(prepare_arg)
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* will be called by the function before performing Allreduce, to initialize the data in sendrecvbuf_.
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* If the result of Allreduce can be recovered directly, then prepare_func will NOT be called
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* \param prepare_arg argument used to pass into the lazy preprocessing function.
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*/
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void Allreduce_(void *sendrecvbuf,
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size_t type_nbytes,
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size_t count,
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IEngine::ReduceFunction red,
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mpi::DataType dtype,
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mpi::OpType op,
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IEngine::PreprocFunction prepare_fun = NULL,
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void *prepare_arg = NULL);
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/*!
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* \brief handle for customized reducer, used to handle customized reduce
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* this class is mainly created for compatiblity issues with MPI's customized reduce
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*/
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class ReduceHandle {
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public:
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// constructor
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ReduceHandle(void);
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// destructor
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~ReduceHandle(void);
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/*!
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* \brief initialize the reduce function,
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* with the type the reduce function needs to deal with
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* the reduce function MUST be communicative
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*/
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void Init(IEngine::ReduceFunction redfunc, size_t type_nbytes);
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/*!
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* \brief customized in-place all reduce operation
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* \param sendrecvbuf the in place send-recv buffer
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* \param type_n4bytes size of the type, in terms of 4bytes
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* \param count number of elements to send
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* \param prepare_func Lazy preprocessing function, lazy prepare_fun(prepare_arg)
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* will be called by the function before performing Allreduce in order to initialize the data in sendrecvbuf_.
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* If the result of Allreduce can be recovered directly, then prepare_func will NOT be called
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* \param prepare_arg argument used to pass into the lazy preprocessing function
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*/
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void Allreduce(void *sendrecvbuf,
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size_t type_nbytes, size_t count,
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IEngine::PreprocFunction prepare_fun = NULL,
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void *prepare_arg = NULL);
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/*! \return the number of bytes occupied by the type */
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static int TypeSize(const MPI::Datatype &dtype);
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protected:
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// handle function field
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void *handle_;
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// reduce function of the reducer
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IEngine::ReduceFunction *redfunc_;
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// handle to the type field
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void *htype_;
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// the created type in 4 bytes
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size_t created_type_nbytes_;
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};
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} // namespace engine
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} // namespace rabit
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#endif // RABIT_ENGINE_H_
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