/mordor/parallel.cpp

  1// Copyright (c) 2009 - Mozy, Inc.
  2
  3#include "parallel.h"
  4
  5#include <boost/scoped_ptr.hpp>
  6
  7#include "assert.h"
  8#include "atomic.h"
  9#include "fibersynchronization.h"
 10
 11namespace Mordor {
 12
 13static Logger::ptr g_log = Log::lookup("mordor:parallel");
 14
 15static
 16void
 17parallel_do_impl(boost::function<void ()> dg, size_t &completed,
 18    size_t total, boost::exception_ptr &exception, Scheduler *scheduler,
 19    Fiber::ptr caller, FiberSemaphore *sem)
 20{
 21    if (sem)
 22        sem->wait();
 23    try {
 24        dg();
 25    } catch (boost::exception &ex) {
 26        removeTopFrames(ex);
 27        exception = boost::current_exception();
 28    } catch (...) {
 29        exception = boost::current_exception();
 30    }
 31    if (sem)
 32        sem->notify();
 33    if (atomicIncrement(completed) == total)
 34        scheduler->schedule(caller);
 35}
 36
 37void
 38parallel_do(const std::vector<boost::function<void ()> > &dgs,
 39    int parallelism)
 40{
 41    size_t completed = 0;
 42    Scheduler *scheduler = Scheduler::getThis();
 43    Fiber::ptr caller = Fiber::getThis();
 44    std::vector<boost::function<void ()> >::const_iterator it;
 45
 46    if (scheduler == NULL || dgs.size() <= 1) {
 47        for(it = dgs.begin(); it != dgs.end(); ++it) {
 48            (*it)();
 49        }
 50        return;
 51    }
 52
 53    MORDOR_ASSERT(parallelism != 0);
 54    boost::scoped_ptr<FiberSemaphore> sem;
 55    if (parallelism != -1)
 56        sem.reset(new FiberSemaphore(parallelism));
 57
 58    std::vector<Fiber::ptr> fibers;
 59    std::vector<boost::exception_ptr> exceptions;
 60    fibers.reserve(dgs.size());
 61    exceptions.resize(dgs.size());
 62    for(size_t i = 0; i < dgs.size(); ++i) {
 63        Fiber::ptr f(new Fiber(boost::bind(&parallel_do_impl, dgs[i],
 64            boost::ref(completed), dgs.size(), boost::ref(exceptions[i]),
 65            scheduler, caller, sem.get())));
 66        fibers.push_back(f);
 67        scheduler->schedule(f);
 68    }
 69
 70    Scheduler::yieldTo();
 71    // Pass the first exception along
 72    // TODO: group exceptions?
 73    for(std::vector<boost::exception_ptr>::iterator it2 = exceptions.begin();
 74        it2 != exceptions.end();
 75        ++it2) {
 76        if (*it2)
 77            Mordor::rethrow_exception(*it2);
 78    }
 79}
 80
 81void
 82parallel_do(const std::vector<boost::function<void ()> > &dgs,
 83            std::vector<Fiber::ptr> &fibers,
 84            int parallelism)
 85{
 86    MORDOR_ASSERT(fibers.size() >= dgs.size());
 87    size_t completed = 0;
 88    Scheduler *scheduler = Scheduler::getThis();
 89    Fiber::ptr caller = Fiber::getThis();
 90    std::vector<boost::function<void ()> >::const_iterator it;
 91
 92    if (scheduler == NULL || dgs.size() <= 1) {
 93        for(it = dgs.begin(); it != dgs.end(); ++it) {
 94            (*it)();
 95        }
 96        return;
 97    }
 98
 99    boost::scoped_ptr<FiberSemaphore> sem;
100    MORDOR_ASSERT(parallelism != 0);
101    if (parallelism != -1)
102        sem.reset(new FiberSemaphore(parallelism));
103
104    std::vector<boost::exception_ptr> exceptions;
105    exceptions.resize(dgs.size());
106    for(size_t i = 0; i < dgs.size(); ++i) {
107        fibers[i]->reset(boost::bind(&parallel_do_impl, dgs[i],
108            boost::ref(completed), dgs.size(), boost::ref(exceptions[i]),
109            scheduler, caller, sem.get()));
110        scheduler->schedule(fibers[i]);
111    }
112    Scheduler::yieldTo();
113    // Make sure all fibers have actually exited, to avoid the caller
114    // immediately calling Fiber::reset, and the Fiber hasn't actually exited
115    // because it is running in a different thread.
116    for (size_t i = 0; i < dgs.size(); ++i)
117        while (fibers[i]->state() == Fiber::EXEC) Scheduler::yield();
118
119    // Pass the first exception along
120    // TODO: group exceptions?
121    for (size_t i = 0; i < dgs.size(); ++i) {
122        if (exceptions[i])
123            Mordor::rethrow_exception(exceptions[i]);
124    }
125}
126
127namespace Detail {
128
129Logger::ptr getLogger()
130{
131    return g_log;
132}
133
134}}