sysprof/lib/util/stackstash.c

/* Sysprof -- Sampling, systemwide CPU profiler
 * Copyright 2004, Red Hat, Inc.
 * Copyright 2004, 2005, Soeren Sandmann
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include "stackstash.h"

struct StackStash
{
    int                 ref_count;
    StackNode *         root;
    GHashTable *        nodes_by_data;
    GDestroyNotify      destroy;

    StackNode *         cached_nodes;
    GPtrArray *         blocks;
};

static void
decorate_node (StackNode *node,
               StackStash *stash)
{
    StackNode *n;

    if (!node)
        return;

    decorate_node (node->siblings, stash);
    decorate_node (node->children, stash);

    node->next = g_hash_table_lookup (stash->nodes_by_data, &node->data);
    g_hash_table_insert (stash->nodes_by_data, &node->data, node);

    /* FIXME: This could be done more efficiently
     * by keeping track of the ancestors we have seen.
     */
    node->toplevel = TRUE;
    for (n = node->parent; n != NULL; n = n->parent)
    {
        if (n->data == node->data)
        {
            node->toplevel = FALSE;
            break;
        }
    }
}

static unsigned int
address_hash (gconstpointer key)
{
    const uint64_t *addr = key;

    return *addr;
}

static gboolean
address_equal (gconstpointer key1, gconstpointer key2)
{
    const uint64_t *addr1 = key1;
    const uint64_t *addr2 = key2;

    return *addr1 == *addr2;
}

static void
stack_stash_decorate (StackStash *stash)
{
    if (stash->nodes_by_data)
        return;

    stash->nodes_by_data = g_hash_table_new (address_hash, address_equal);

    decorate_node (stash->root, stash);
}

static void
free_key (gpointer key,
          gpointer value,
          gpointer data)
{
    GDestroyNotify destroy = data;
    uint64_t u64 = *(uint64_t *)key;

    destroy (U64_TO_POINTER (u64));
}

static void
stack_stash_undecorate (StackStash *stash)
{
    if (stash->nodes_by_data)
    {
        if (stash->destroy)
        {
            g_hash_table_foreach (
                stash->nodes_by_data, free_key, stash->destroy);
        }

        g_hash_table_destroy (stash->nodes_by_data);
        stash->nodes_by_data = NULL;
    }
}

static GHashTable *
get_nodes_by_data (StackStash *stash)
{
    if (!stash->nodes_by_data)
        stack_stash_decorate (stash);

    return stash->nodes_by_data;
}

StackNode *
stack_node_new (StackStash *stash)
{
    StackNode *node;

    if (!stash->cached_nodes)
    {
#define BLOCK_SIZE 32768
#define N_NODES (BLOCK_SIZE / sizeof (StackNode))

        StackNode *block = g_malloc (BLOCK_SIZE);
        guint i;

        for (i = 0; i < N_NODES; ++i)
        {
            block[i].next = stash->cached_nodes;
            stash->cached_nodes = &(block[i]);
        }

        g_ptr_array_add (stash->blocks, block);
    }

    node = stash->cached_nodes;
    stash->cached_nodes = node->next;

    node->siblings = NULL;
    node->children = NULL;
    node->data = 0;
    node->parent = NULL;
    node->size = 0;
    node->next = NULL;
    node->total = 0;

    return node;
}

/* "destroy", if non-NULL, is called once on every address */
static StackStash *
create_stack_stash (GDestroyNotify destroy)
{
    StackStash *stash = g_new (StackStash, 1);

    stash->root = NULL;
    stash->nodes_by_data = NULL;
    stash->ref_count = 1;
    stash->destroy = destroy;

    stash->cached_nodes = NULL;
    stash->blocks = g_ptr_array_new ();

    return stash;
}

/* Stach */
StackStash *
stack_stash_new (GDestroyNotify destroy)
{
    return create_stack_stash (destroy);
}


static void
stack_stash_free (StackStash *stash)
{
    guint i;

    stack_stash_undecorate (stash);

    for (i = 0; i < stash->blocks->len; ++i)
        g_free (stash->blocks->pdata[i]);

    g_ptr_array_free (stash->blocks, TRUE);

    g_free (stash);
}

StackNode *
stack_stash_add_trace (StackStash     *stash,
                       const uint64_t *addrs,
                       int             n_addrs,
                       int             size)
{
    StackNode **location = &(stash->root);
    StackNode *parent = NULL;
    int i;

    if (!n_addrs)
        return NULL;

    if (stash->nodes_by_data)
        stack_stash_undecorate (stash);

    for (i = n_addrs - 1; i >= 0; --i)
    {
        StackNode *match = NULL;
        StackNode *prev;

        /* FIXME: On x86-64 we don't get proper stacktraces which means
         * each node can have tons of children. That makes this loop
         * here show up on profiles.
         *
         * Not sure what can be done about it aside from actually fixing
         * x86-64 to get stacktraces.
         */
        prev = NULL;
        for (match = *location; match; prev = match, match = match->siblings)
        {
            if (match->data == addrs[i])
            {
                if (prev)
                {
                    /* move to front */
                    prev->siblings = match->siblings;
                    match->siblings = *location;
                    *location = match;
                }

                break;
            }
        }

        if (!match)
        {
            match = stack_node_new (stash);
            match->data = addrs[i];
            match->siblings = *location;
            match->parent = parent;
            *location = match;
        }

        match->total += size;

        location = &(match->children);
        parent = match;
    }

    parent->size += size;

    return parent;
}

static void
do_callback (StackNode *node,
             StackLink *trace,
             StackFunction func,
             gpointer data)
{
    StackLink link;

    if (trace)
        trace->prev = &link;

    link.next = trace;
    link.prev = NULL;

    while (node)
    {
        link.data = node->data;

        if (node->size)
            func (&link, node->size, data);

        do_callback (node->children, &link, func, data);

        node = node->siblings;
    }

    if (trace)
        trace->prev = NULL;
}

void
stack_stash_foreach (StackStash      *stash,
                     StackFunction    stack_func,
                     gpointer         data)
{
    do_callback (stash->root, NULL, stack_func, data);
}

void
stack_node_foreach_trace (StackNode     *node,
                          StackFunction  func,
                          gpointer       data)
{
    StackLink link;

    link.next = NULL;
    link.data = node->data;
    link.prev = NULL;

    if (node->size)
        func (&link, node->size, data);

    do_callback (node->children, &link, func, data);
}

void
stack_stash_unref (StackStash *stash)
{
    stash->ref_count--;
    if (stash->ref_count == 0)
        stack_stash_free (stash);
}

StackStash *
stack_stash_ref (StackStash *stash)
{
    stash->ref_count++;
    return stash;
}

StackNode *
stack_stash_find_node (StackStash      *stash,
                       gpointer         data)
{
    uint64_t u64 = POINTER_TO_U64 (data);

    g_return_val_if_fail (stash != NULL, NULL);

    return g_hash_table_lookup (get_nodes_by_data (stash), &u64);
}

typedef struct
{
    StackNodeFunc func;
    gpointer      data;
} Info;

static void
do_foreach (gpointer key, gpointer value, gpointer data)
{
    Info *info = data;

    info->func (value, info->data);
}

void
stack_stash_foreach_by_address (StackStash *stash,
                                StackNodeFunc func,
                                gpointer      data)
{
    Info info;
    info.func = func;
    info.data = data;

    g_hash_table_foreach (get_nodes_by_data (stash), do_foreach, &info);
}

StackNode  *
stack_stash_get_root (StackStash *stash)
{
    return stash->root;
}

void
stack_stash_set_root (StackStash     *stash,
                      StackNode      *root)
{
    g_return_if_fail (stash->root == NULL);

    stash->root = root;
}