test_hashtab_thrash.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2012, David M. Lee, II
 *
 * David M. Lee, II <dlee@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */
 
/*
 *! \file \brief Thrash a hash table, for fun and profit.
 *
 * \author\verbatim David M. Lee, II <dlee@digium.com> \endverbatim
 *
 * Inspired by the original hashtest.c by Steve Murphy <murf@digium.com>.  This test runs
 * several threads manipulating a concurrent hastab to see if they maintain
 * consistency. While the tests attempt to check consistency and error normally, threading
 * errors often result in segfaults.
 * \ingroup tests
 */
 
/*** MODULEINFO
    <depend>TEST_FRAMEWORK</depend>
    <support_level>core</support_level>
 ***/
 
#include "asterisk.h"
 
#include <pthread.h>
#include "asterisk/hashtab.h"
#include "asterisk/lock.h"
#include "asterisk/module.h"
#include "asterisk/test.h"
#include "asterisk/time.h"
#include "asterisk/utils.h"
 
#define MAX_HASH_ENTRIES 30000
#define MAX_TEST_SECONDS 60
 
struct hash_test {
    /*! Unit under test */
    struct ast_hashtab *to_be_thrashed;
    /*! Number of entries to insert in the grow thread. */
    int max_grow;
    /*! Number of entries added by the grow thread. */
    int grow_count;
    /*! Entries preloaded into the hashtab; to be deleted by the shrink thread */
    int preload;
    /*! When to give up on the tests */
    struct timeval deadline;
    /*! The actual test object */
    struct ast_test *test;
};
 
static int is_timed_out(struct hash_test const *data) {
    struct timeval now = ast_tvnow();
    int val = ast_tvdiff_us(data->deadline, now) < 0;
    if (val) {
        /* tv_usec is suseconds_t, which could be int or long */
        ast_test_status_update(data->test, "Now: %ld.%06ld Deadline: %ld.%06ld\n",
            now.tv_sec, (long)now.tv_usec,
            data->deadline.tv_sec, (long)data->deadline.tv_usec);
    }
    return val;
}
 
/*! \brief Create test element */
static char *ht_new(int i)
{
    const int buflen = 12;
    char *keybuf = ast_malloc(buflen);
    int needed;
    if (keybuf == NULL) {
        return NULL;
    }
    needed = snprintf(keybuf, buflen, "key%08x", (unsigned)i);
    ast_assert(needed + 1 <= buflen);
    return keybuf;
}
 
/*! \brief Free test element */
static void ht_delete(void *obj)
{
    ast_free(obj);
}
 
/*! \brief Grow the hash data as specified */
static void *hash_test_grow(void *d)
{
    struct hash_test *data = d;
    int i;
 
    for (i = 0; i < data->max_grow; ++i) {
        char *obj;
        if (is_timed_out(data)) {
            return "Growth timed out";
        }
        obj = ht_new(i);
        if (obj == NULL) {
            return "Allocation failed";
        }
        ast_hashtab_insert_immediate(data->to_be_thrashed, obj);
        ast_atomic_fetchadd_int(&data->grow_count, 1);
    }
    return NULL;
}
 
/*! Randomly lookup data in the hash */
static void *hash_test_lookup(void *d)
{
    struct hash_test *data = d;
    int max;
    unsigned seed = time(NULL);
 
    /* ast_atomic_fetchadd_int provide a memory fence so that the optimizer doesn't
     * optimize away reads.
     */
    while ((max = ast_atomic_fetchadd_int(&data->grow_count, 0)) < data->max_grow) {
        int i;
        char *obj;
        int is_in_hashtab;
 
        if (is_timed_out(data)) {
            return "Lookup timed out";
        }
 
        if (max == 0) {
            /* No data yet; yield and try again */
            sched_yield();
            continue;
        }
 
        /* Randomly lookup one object from the hash */
        i = rand_r(&seed) % max;
        obj = ht_new(i);
        if (obj == NULL) {
            return "Allocation failed.";
        }
        is_in_hashtab = (ast_hashtab_lookup(data->to_be_thrashed, obj) != NULL);
        ht_delete(obj);
        if (!is_in_hashtab) {
            return "key unexpectedly missing";
        }
    }
 
    return NULL;
}
 
/*! Delete entries from the hash */
static void *hash_test_shrink(void *d)
{
    const struct hash_test *data = d;
    int i;
 
    for (i = 1; i < data->preload; ++i) {
        char *obj = ht_new(-i);
        char *from_hashtab;
        int deleted;
 
        if (obj == NULL) {
            return "Allocation failed";
        }
        from_hashtab = ast_hashtab_remove_object_via_lookup(data->to_be_thrashed, obj);
        deleted = from_hashtab != NULL;
 
        ht_delete(obj);
        ht_delete(from_hashtab);
        if (!deleted) {
            return "could not delete object";
        }
        if (is_timed_out(data)) {
            return "Shrink timed out";
        }
    }
    return NULL;
}
 
/*! Continuously iterate through all the entries in the hash */
static void *hash_test_count(void *d)
{
    const struct hash_test *data = d;
    int count = 0;
    int last_count = 0;
 
    while (count < data->max_grow) {
        struct ast_hashtab_iter *it = ast_hashtab_start_write_traversal(data->to_be_thrashed);
        char *ht = ast_hashtab_next(it);
        last_count = count;
        count = 0;
        while (ht) {
            /* only count keys added by grow thread */
            if (strncmp(ht, "key0", 4) == 0) {
                ++count;
            }
            ht = ast_hashtab_next(it);
        }
        ast_hashtab_end_traversal(it);
 
        if (last_count == count) {
            /* Give other threads ample chance to run, note that using sched_yield here does not
             * provide enough of a chance and can cause this thread to starve others.
             */
            usleep(1);
        } else if (last_count > count) {
            /* Make sure the hashtable never shrinks */
            return "hashtab unexpectedly shrank";
        }
 
        if (is_timed_out(data)) {
            return "Count timed out";
        }
    }
 
    /* Successfully iterated over all of the expected elements */
    return NULL;
}
 
AST_TEST_DEFINE(hash_test)
{
    enum ast_test_result_state res = AST_TEST_PASS;
    struct hash_test data = {};
    pthread_t grow_thread, count_thread, lookup_thread, shrink_thread;
    void *thread_results;
    int i;
 
    switch (cmd) {
    case TEST_INIT:
        info->name = "thrash";
        info->category = "/main/hashtab/";
        info->summary = "Testing hashtab concurrency";
        info->description = "Test hashtab concurrency correctness.";
        return AST_TEST_NOT_RUN;
    case TEST_EXECUTE:
        break;
    }
 
    ast_test_status_update(test, "Executing hash concurrency test...\n");
    data.test = test;
    data.preload = MAX_HASH_ENTRIES / 2;
    data.max_grow = MAX_HASH_ENTRIES - data.preload;
    data.deadline = ast_tvadd(ast_tvnow(), ast_tv(MAX_TEST_SECONDS, 0));
    data.to_be_thrashed = ast_hashtab_create(MAX_HASH_ENTRIES / 100,
        ast_hashtab_compare_strings_nocase, ast_hashtab_resize_java,
        ast_hashtab_newsize_java, ast_hashtab_hash_string_nocase, 1);
 
    if (data.to_be_thrashed == NULL) {
        ast_test_status_update(test, "Allocation failed\n");
        /* Nothing needs to be freed; early return is fine */
        return AST_TEST_FAIL;
    }
 
 
    /* preload with data to delete */
    for (i = 1; i < data.preload; ++i) {
        char *obj = ht_new(-i);
        if (obj == NULL) {
            ast_test_status_update(test, "Allocation failed\n");
            ast_hashtab_destroy(data.to_be_thrashed, ht_delete);
            return AST_TEST_FAIL;
        }
        ast_hashtab_insert_immediate(data.to_be_thrashed, obj);
    }
 
    /* add data.max_grow entries to the hashtab */
    ast_pthread_create(&grow_thread, NULL, hash_test_grow, &data);
    /* continually count the keys added by the grow thread */
    ast_pthread_create(&count_thread, NULL, hash_test_count, &data);
    /* continually lookup keys added by the grow thread */
    ast_pthread_create(&lookup_thread, NULL, hash_test_lookup, &data);
    /* delete all keys preloaded into the hashtab */
    ast_pthread_create(&shrink_thread, NULL, hash_test_shrink, &data);
 
    pthread_join(grow_thread, &thread_results);
    if (thread_results != NULL) {
        ast_test_status_update(test, "Growth thread failed: %s\n",
            (char *)thread_results);
        res = AST_TEST_FAIL;
    }
 
    pthread_join(count_thread, &thread_results);
    if (thread_results != NULL) {
        ast_test_status_update(test, "Count thread failed: %s\n",
            (char *)thread_results);
        res = AST_TEST_FAIL;
    }
 
    pthread_join(lookup_thread, &thread_results);
    if (thread_results != NULL) {
        ast_test_status_update(test, "Lookup thread failed: %s\n",
            (char *)thread_results);
        res = AST_TEST_FAIL;
    }
 
    pthread_join(shrink_thread, &thread_results);
    if (thread_results != NULL) {
        ast_test_status_update(test, "Shrink thread failed: %s\n",
            (char *)thread_results);
        res = AST_TEST_FAIL;
    }
 
    if (ast_hashtab_size(data.to_be_thrashed) != data.max_grow) {
        ast_test_status_update(test,
            "Invalid hashtab size. Expected: %d, Actual: %d\n",
            data.max_grow, ast_hashtab_size(data.to_be_thrashed));
        res = AST_TEST_FAIL;
    }
 
    ast_hashtab_destroy(data.to_be_thrashed, ht_delete);
    return res;
}
 
static int unload_module(void)
{
    AST_TEST_UNREGISTER(hash_test);
    return 0;
}
 
static int load_module(void)
{
    AST_TEST_REGISTER(hash_test);
    return AST_MODULE_LOAD_SUCCESS;
}
 
AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Hash test");