view contrib/python-zstandard/zstd/common/pool.c @ 46472:98e39f04d60e

upgrade: implement partial upgrade for upgrading persistent-nodemap

Upgrading repositories to use persistent nodemap should be fast and easy as it
requires only two things:

1) Updating the requirements
2) Writing a persistent-nodemap on disk

For both of the steps above, we don't need to edit existing revlogs.

This patch makes upgrade only do the above mentioned two steps if we are
only upgarding to use persistent-nodemap feature.

Since `nodemap.persist_nodemap()` assumes that there exists a nodemap file for
the given revlog if we are trying to call it, this patch adds `force` argument
to create a file if does not exist which is true in our upgrade case.

The test changes demonstrate that we no longer write nodemap files for manifest
after upgrade which I think is desirable.

Differential Revision: https://phab.mercurial-scm.org/D9936

/*
 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under both the BSD-style license (found in the
 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
 * in the COPYING file in the root directory of this source tree).
 * You may select, at your option, one of the above-listed licenses.
 */


/* ======   Dependencies   ======= */
#include <stddef.h>    /* size_t */
#include "debug.h"     /* assert */
#include "zstd_internal.h"  /* ZSTD_malloc, ZSTD_free */
#include "pool.h"

/* ======   Compiler specifics   ====== */
#if defined(_MSC_VER)
#  pragma warning(disable : 4204)        /* disable: C4204: non-constant aggregate initializer */
#endif


#ifdef ZSTD_MULTITHREAD

#include "threading.h"   /* pthread adaptation */

/* A job is a function and an opaque argument */
typedef struct POOL_job_s {
    POOL_function function;
    void *opaque;
} POOL_job;

struct POOL_ctx_s {
    ZSTD_customMem customMem;
    /* Keep track of the threads */
    ZSTD_pthread_t* threads;
    size_t threadCapacity;
    size_t threadLimit;

    /* The queue is a circular buffer */
    POOL_job *queue;
    size_t queueHead;
    size_t queueTail;
    size_t queueSize;

    /* The number of threads working on jobs */
    size_t numThreadsBusy;
    /* Indicates if the queue is empty */
    int queueEmpty;

    /* The mutex protects the queue */
    ZSTD_pthread_mutex_t queueMutex;
    /* Condition variable for pushers to wait on when the queue is full */
    ZSTD_pthread_cond_t queuePushCond;
    /* Condition variables for poppers to wait on when the queue is empty */
    ZSTD_pthread_cond_t queuePopCond;
    /* Indicates if the queue is shutting down */
    int shutdown;
};

/* POOL_thread() :
 * Work thread for the thread pool.
 * Waits for jobs and executes them.
 * @returns : NULL on failure else non-null.
 */
static void* POOL_thread(void* opaque) {
    POOL_ctx* const ctx = (POOL_ctx*)opaque;
    if (!ctx) { return NULL; }
    for (;;) {
        /* Lock the mutex and wait for a non-empty queue or until shutdown */
        ZSTD_pthread_mutex_lock(&ctx->queueMutex);

        while ( ctx->queueEmpty
            || (ctx->numThreadsBusy >= ctx->threadLimit) ) {
            if (ctx->shutdown) {
                /* even if !queueEmpty, (possible if numThreadsBusy >= threadLimit),
                 * a few threads will be shutdown while !queueEmpty,
                 * but enough threads will remain active to finish the queue */
                ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
                return opaque;
            }
            ZSTD_pthread_cond_wait(&ctx->queuePopCond, &ctx->queueMutex);
        }
        /* Pop a job off the queue */
        {   POOL_job const job = ctx->queue[ctx->queueHead];
            ctx->queueHead = (ctx->queueHead + 1) % ctx->queueSize;
            ctx->numThreadsBusy++;
            ctx->queueEmpty = ctx->queueHead == ctx->queueTail;
            /* Unlock the mutex, signal a pusher, and run the job */
            ZSTD_pthread_cond_signal(&ctx->queuePushCond);
            ZSTD_pthread_mutex_unlock(&ctx->queueMutex);

            job.function(job.opaque);

            /* If the intended queue size was 0, signal after finishing job */
            ZSTD_pthread_mutex_lock(&ctx->queueMutex);
            ctx->numThreadsBusy--;
            if (ctx->queueSize == 1) {
                ZSTD_pthread_cond_signal(&ctx->queuePushCond);
            }
            ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
        }
    }  /* for (;;) */
    assert(0);  /* Unreachable */
}

POOL_ctx* POOL_create(size_t numThreads, size_t queueSize) {
    return POOL_create_advanced(numThreads, queueSize, ZSTD_defaultCMem);
}

POOL_ctx* POOL_create_advanced(size_t numThreads, size_t queueSize,
                               ZSTD_customMem customMem) {
    POOL_ctx* ctx;
    /* Check parameters */
    if (!numThreads) { return NULL; }
    /* Allocate the context and zero initialize */
    ctx = (POOL_ctx*)ZSTD_calloc(sizeof(POOL_ctx), customMem);
    if (!ctx) { return NULL; }
    /* Initialize the job queue.
     * It needs one extra space since one space is wasted to differentiate
     * empty and full queues.
     */
    ctx->queueSize = queueSize + 1;
    ctx->queue = (POOL_job*)ZSTD_malloc(ctx->queueSize * sizeof(POOL_job), customMem);
    ctx->queueHead = 0;
    ctx->queueTail = 0;
    ctx->numThreadsBusy = 0;
    ctx->queueEmpty = 1;
    {
        int error = 0;
        error |= ZSTD_pthread_mutex_init(&ctx->queueMutex, NULL);
        error |= ZSTD_pthread_cond_init(&ctx->queuePushCond, NULL);
        error |= ZSTD_pthread_cond_init(&ctx->queuePopCond, NULL);
        if (error) { POOL_free(ctx); return NULL; }
    }
    ctx->shutdown = 0;
    /* Allocate space for the thread handles */
    ctx->threads = (ZSTD_pthread_t*)ZSTD_malloc(numThreads * sizeof(ZSTD_pthread_t), customMem);
    ctx->threadCapacity = 0;
    ctx->customMem = customMem;
    /* Check for errors */
    if (!ctx->threads || !ctx->queue) { POOL_free(ctx); return NULL; }
    /* Initialize the threads */
    {   size_t i;
        for (i = 0; i < numThreads; ++i) {
            if (ZSTD_pthread_create(&ctx->threads[i], NULL, &POOL_thread, ctx)) {
                ctx->threadCapacity = i;
                POOL_free(ctx);
                return NULL;
        }   }
        ctx->threadCapacity = numThreads;
        ctx->threadLimit = numThreads;
    }
    return ctx;
}

/*! POOL_join() :
    Shutdown the queue, wake any sleeping threads, and join all of the threads.
*/
static void POOL_join(POOL_ctx* ctx) {
    /* Shut down the queue */
    ZSTD_pthread_mutex_lock(&ctx->queueMutex);
    ctx->shutdown = 1;
    ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
    /* Wake up sleeping threads */
    ZSTD_pthread_cond_broadcast(&ctx->queuePushCond);
    ZSTD_pthread_cond_broadcast(&ctx->queuePopCond);
    /* Join all of the threads */
    {   size_t i;
        for (i = 0; i < ctx->threadCapacity; ++i) {
            ZSTD_pthread_join(ctx->threads[i], NULL);  /* note : could fail */
    }   }
}

void POOL_free(POOL_ctx *ctx) {
    if (!ctx) { return; }
    POOL_join(ctx);
    ZSTD_pthread_mutex_destroy(&ctx->queueMutex);
    ZSTD_pthread_cond_destroy(&ctx->queuePushCond);
    ZSTD_pthread_cond_destroy(&ctx->queuePopCond);
    ZSTD_free(ctx->queue, ctx->customMem);
    ZSTD_free(ctx->threads, ctx->customMem);
    ZSTD_free(ctx, ctx->customMem);
}



size_t POOL_sizeof(POOL_ctx *ctx) {
    if (ctx==NULL) return 0;  /* supports sizeof NULL */
    return sizeof(*ctx)
        + ctx->queueSize * sizeof(POOL_job)
        + ctx->threadCapacity * sizeof(ZSTD_pthread_t);
}


/* @return : 0 on success, 1 on error */
static int POOL_resize_internal(POOL_ctx* ctx, size_t numThreads)
{
    if (numThreads <= ctx->threadCapacity) {
        if (!numThreads) return 1;
        ctx->threadLimit = numThreads;
        return 0;
    }
    /* numThreads > threadCapacity */
    {   ZSTD_pthread_t* const threadPool = (ZSTD_pthread_t*)ZSTD_malloc(numThreads * sizeof(ZSTD_pthread_t), ctx->customMem);
        if (!threadPool) return 1;
        /* replace existing thread pool */
        memcpy(threadPool, ctx->threads, ctx->threadCapacity * sizeof(*threadPool));
        ZSTD_free(ctx->threads, ctx->customMem);
        ctx->threads = threadPool;
        /* Initialize additional threads */
        {   size_t threadId;
            for (threadId = ctx->threadCapacity; threadId < numThreads; ++threadId) {
                if (ZSTD_pthread_create(&threadPool[threadId], NULL, &POOL_thread, ctx)) {
                    ctx->threadCapacity = threadId;
                    return 1;
            }   }
    }   }
    /* successfully expanded */
    ctx->threadCapacity = numThreads;
    ctx->threadLimit = numThreads;
    return 0;
}

/* @return : 0 on success, 1 on error */
int POOL_resize(POOL_ctx* ctx, size_t numThreads)
{
    int result;
    if (ctx==NULL) return 1;
    ZSTD_pthread_mutex_lock(&ctx->queueMutex);
    result = POOL_resize_internal(ctx, numThreads);
    ZSTD_pthread_cond_broadcast(&ctx->queuePopCond);
    ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
    return result;
}

/**
 * Returns 1 if the queue is full and 0 otherwise.
 *
 * When queueSize is 1 (pool was created with an intended queueSize of 0),
 * then a queue is empty if there is a thread free _and_ no job is waiting.
 */
static int isQueueFull(POOL_ctx const* ctx) {
    if (ctx->queueSize > 1) {
        return ctx->queueHead == ((ctx->queueTail + 1) % ctx->queueSize);
    } else {
        return (ctx->numThreadsBusy == ctx->threadLimit) ||
               !ctx->queueEmpty;
    }
}


static void POOL_add_internal(POOL_ctx* ctx, POOL_function function, void *opaque)
{
    POOL_job const job = {function, opaque};
    assert(ctx != NULL);
    if (ctx->shutdown) return;

    ctx->queueEmpty = 0;
    ctx->queue[ctx->queueTail] = job;
    ctx->queueTail = (ctx->queueTail + 1) % ctx->queueSize;
    ZSTD_pthread_cond_signal(&ctx->queuePopCond);
}

void POOL_add(POOL_ctx* ctx, POOL_function function, void* opaque)
{
    assert(ctx != NULL);
    ZSTD_pthread_mutex_lock(&ctx->queueMutex);
    /* Wait until there is space in the queue for the new job */
    while (isQueueFull(ctx) && (!ctx->shutdown)) {
        ZSTD_pthread_cond_wait(&ctx->queuePushCond, &ctx->queueMutex);
    }
    POOL_add_internal(ctx, function, opaque);
    ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
}


int POOL_tryAdd(POOL_ctx* ctx, POOL_function function, void* opaque)
{
    assert(ctx != NULL);
    ZSTD_pthread_mutex_lock(&ctx->queueMutex);
    if (isQueueFull(ctx)) {
        ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
        return 0;
    }
    POOL_add_internal(ctx, function, opaque);
    ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
    return 1;
}


#else  /* ZSTD_MULTITHREAD  not defined */

/* ========================== */
/* No multi-threading support */
/* ========================== */


/* We don't need any data, but if it is empty, malloc() might return NULL. */
struct POOL_ctx_s {
    int dummy;
};
static POOL_ctx g_ctx;

POOL_ctx* POOL_create(size_t numThreads, size_t queueSize) {
    return POOL_create_advanced(numThreads, queueSize, ZSTD_defaultCMem);
}

POOL_ctx* POOL_create_advanced(size_t numThreads, size_t queueSize, ZSTD_customMem customMem) {
    (void)numThreads;
    (void)queueSize;
    (void)customMem;
    return &g_ctx;
}

void POOL_free(POOL_ctx* ctx) {
    assert(!ctx || ctx == &g_ctx);
    (void)ctx;
}

int POOL_resize(POOL_ctx* ctx, size_t numThreads) {
    (void)ctx; (void)numThreads;
    return 0;
}

void POOL_add(POOL_ctx* ctx, POOL_function function, void* opaque) {
    (void)ctx;
    function(opaque);
}

int POOL_tryAdd(POOL_ctx* ctx, POOL_function function, void* opaque) {
    (void)ctx;
    function(opaque);
    return 1;
}

size_t POOL_sizeof(POOL_ctx* ctx) {
    if (ctx==NULL) return 0;  /* supports sizeof NULL */
    assert(ctx == &g_ctx);
    return sizeof(*ctx);
}

#endif  /* ZSTD_MULTITHREAD */