/*
 * Copyright (C) 2009-2010, Frederic Weisbecker <fweisbec@gmail.com>
 *
 * Handle the callchains from the stream in an ad-hoc radix tree and then
 * sort them in an rbtree.
 *
 * Using a radix for code path provides a fast retrieval and factorizes
 * memory use. Also that lets us use the paths in a hierarchical graph view.
 *
 */

#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>
#include <errno.h>
#include <math.h>

#include "util.h"
#include "callchain.h"

bool ip_callchain__valid(struct ip_callchain *chain, const event_t *event)
{
        unsigned int chain_size = event->header.size;
        chain_size -= (unsigned long)&event->ip.__more_data - (unsigned long)event;
        return chain->nr * sizeof(u64) <= chain_size;
}

#define chain_for_each_child(child, parent)     \
        list_for_each_entry(child, &parent->children, brothers)

#define chain_for_each_child_safe(child, next, parent)  \
        list_for_each_entry_safe(child, next, &parent->children, brothers)

static void
rb_insert_callchain(struct rb_root *root, struct callchain_node *chain,
                    enum chain_mode mode)
{
        struct rb_node **p = &root->rb_node;
        struct rb_node *parent = NULL;
        struct callchain_node *rnode;
        u64 chain_cumul = cumul_hits(chain);

        while (*p) {
                u64 rnode_cumul;

                parent = *p;
                rnode = rb_entry(parent, struct callchain_node, rb_node);
                rnode_cumul = cumul_hits(rnode);

                switch (mode) {
                case CHAIN_FLAT:
                        if (rnode->hit < chain->hit)
                                p = &(*p)->rb_left;
                        else
                                p = &(*p)->rb_right;
                        break;
                case CHAIN_GRAPH_ABS: /* Falldown */
                case CHAIN_GRAPH_REL:
                        if (rnode_cumul < chain_cumul)
                                p = &(*p)->rb_left;
                        else
                                p = &(*p)->rb_right;
                        break;
                case CHAIN_NONE:
                default:
                        break;
                }
        }

        rb_link_node(&chain->rb_node, parent, p);
        rb_insert_color(&chain->rb_node, root);
}

static void
__sort_chain_flat(struct rb_root *rb_root, struct callchain_node *node,
                  u64 min_hit)
{
        struct callchain_node *child;

        chain_for_each_child(child, node)
                __sort_chain_flat(rb_root, child, min_hit);

        if (node->hit && node->hit >= min_hit)
                rb_insert_callchain(rb_root, node, CHAIN_FLAT);
}

/*
 * Once we get every callchains from the stream, we can now
 * sort them by hit
 */
static void
sort_chain_flat(struct rb_root *rb_root, struct callchain_root *root,
                u64 min_hit, struct callchain_param *param __used)
{
        __sort_chain_flat(rb_root, &root->node, min_hit);
}

static void __sort_chain_graph_abs(struct callchain_node *node,
                                   u64 min_hit)
{
        struct callchain_node *child;

        node->rb_root = RB_ROOT;

        chain_for_each_child(child, node) {
                __sort_chain_graph_abs(child, min_hit);
                if (cumul_hits(child) >= min_hit)
                        rb_insert_callchain(&node->rb_root, child,
                                            CHAIN_GRAPH_ABS);
        }
}

static void
sort_chain_graph_abs(struct rb_root *rb_root, struct callchain_root *chain_root,
                     u64 min_hit, struct callchain_param *param __used)
{
        __sort_chain_graph_abs(&chain_root->node, min_hit);
        rb_root->rb_node = chain_root->node.rb_root.rb_node;
}

static void __sort_chain_graph_rel(struct callchain_node *node,
                                   double min_percent)
{
        struct callchain_node *child;
        u64 min_hit;

        node->rb_root = RB_ROOT;
        min_hit = ceil(node->children_hit * min_percent);

        chain_for_each_child(child, node) {
                __sort_chain_graph_rel(child, min_percent);
                if (cumul_hits(child) >= min_hit)
                        rb_insert_callchain(&node->rb_root, child,
                                            CHAIN_GRAPH_REL);
        }
}

static void
sort_chain_graph_rel(struct rb_root *rb_root, struct callchain_root *chain_root,
                     u64 min_hit __used, struct callchain_param *param)
{
        __sort_chain_graph_rel(&chain_root->node, param->min_percent / 100.0);
        rb_root->rb_node = chain_root->node.rb_root.rb_node;
}

int register_callchain_param(struct callchain_param *param)
{
        switch (param->mode) {
        case CHAIN_GRAPH_ABS:
                param->sort = sort_chain_graph_abs;
                break;
        case CHAIN_GRAPH_REL:
                param->sort = sort_chain_graph_rel;
                break;
        case CHAIN_FLAT:
                param->sort = sort_chain_flat;
                break;
        case CHAIN_NONE:
        default:
                return -1;
        }
        return 0;
}

/*
 * Create a child for a parent. If inherit_children, then the new child
 * will become the new parent of it's parent children
 */
static struct callchain_node *
create_child(struct callchain_node *parent, bool inherit_children)
{
        struct callchain_node *new;

        new = zalloc(sizeof(*new));
        if (!new) {
                perror("not enough memory to create child for code path tree");
                return NULL;
        }
        new->parent = parent;
        INIT_LIST_HEAD(&new->children);
        INIT_LIST_HEAD(&new->val);

        if (inherit_children) {
                struct callchain_node *next;

                list_splice(&parent->children, &new->children);
                INIT_LIST_HEAD(&parent->children);

                chain_for_each_child(next, new)
                        next->parent = new;
        }
        list_add_tail(&new->brothers, &parent->children);

        return new;
}


struct resolved_ip {
        u64               ip;
        struct map_symbol ms;
};

struct resolved_chain {
        u64                     nr;
        struct resolved_ip      ips[0];
};


/*
 * Fill the node with callchain values
 */
static void
fill_node(struct callchain_node *node, struct resolved_chain *chain, int start)
{
        unsigned int i;

        for (i = start; i < chain->nr; i++) {
                struct callchain_list *call;

                call = zalloc(sizeof(*call));
                if (!call) {
                        perror("not enough memory for the code path tree");
                        return;
                }
                call->ip = chain->ips[i].ip;
                call->ms = chain->ips[i].ms;
                list_add_tail(&call->list, &node->val);
        }
        node->val_nr = chain->nr - start;
        if (!node->val_nr)
                pr_warning("Warning: empty node in callchain tree\n");
}

static void
add_child(struct callchain_node *parent, struct resolved_chain *chain,
          int start, u64 period)
{
        struct callchain_node *new;

        new = create_child(parent, false);
        fill_node(new, chain, start);

        new->children_hit = 0;
        new->hit = period;
}

/*
 * Split the parent in two parts (a new child is created) and
 * give a part of its callchain to the created child.
 * Then create another child to host the given callchain of new branch
 */
static void
split_add_child(struct callchain_node *parent, struct resolved_chain *chain,
                struct callchain_list *to_split, int idx_parents, int idx_local,
                u64 period)
{
        struct callchain_node *new;
        struct list_head *old_tail;
        unsigned int idx_total = idx_parents + idx_local;

        /* split */
        new = create_child(parent, true);

        /* split the callchain and move a part to the new child */
        old_tail = parent->val.prev;
        list_del_range(&to_split->list, old_tail);
        new->val.next = &to_split->list;
        new->val.prev = old_tail;
        to_split->list.prev = &new->val;
        old_tail->next = &new->val;

        /* split the hits */
        new->hit = parent->hit;
        new->children_hit = parent->children_hit;
        parent->children_hit = cumul_hits(new);
        new->val_nr = parent->val_nr - idx_local;
        parent->val_nr = idx_local;

        /* create a new child for the new branch if any */
        if (idx_total < chain->nr) {
                parent->hit = 0;
                add_child(parent, chain, idx_total, period);
                parent->children_hit += period;
        } else {
                parent->hit = period;
        }
}

static int
append_chain(struct callchain_node *root, struct resolved_chain *chain,
             unsigned int start, u64 period);

static void
append_chain_children(struct callchain_node *root, struct resolved_chain *chain,
                      unsigned int start, u64 period)
{
        struct callchain_node *rnode;

        /* lookup in childrens */
        chain_for_each_child(rnode, root) {
                unsigned int ret = append_chain(rnode, chain, start, period);

                if (!ret)
                        goto inc_children_hit;
        }
        /* nothing in children, add to the current node */
        add_child(root, chain, start, period);

inc_children_hit:
        root->children_hit += period;
}

static int
append_chain(struct callchain_node *root, struct resolved_chain *chain,
             unsigned int start, u64 period)
{
        struct callchain_list *cnode;
        unsigned int i = start;
        bool found = false;

        /*
         * Lookup in the current node
         * If we have a symbol, then compare the start to match
         * anywhere inside a function.
         */
        list_for_each_entry(cnode, &root->val, list) {
                struct symbol *sym;

                if (i == chain->nr)
                        break;

                sym = chain->ips[i].ms.sym;

                if (cnode->ms.sym && sym) {
                        if (cnode->ms.sym->start != sym->start)
                                break;
                } else if (cnode->ip != chain->ips[i].ip)
                        break;

                if (!found)
                        found = true;
                i++;
        }

        /* matches not, relay on the parent */
        if (!found)
                return -1;

        /* we match only a part of the node. Split it and add the new chain */
        if (i - start < root->val_nr) {
                split_add_child(root, chain, cnode, start, i - start, period);
                return 0;
        }

        /* we match 100% of the path, increment the hit */
        if (i - start == root->val_nr && i == chain->nr) {
                root->hit += period;
                return 0;
        }

        /* We match the node and still have a part remaining */
        append_chain_children(root, chain, i, period);

        return 0;
}

static void filter_context(struct ip_callchain *old, struct resolved_chain *new,
                           struct map_symbol *syms)
{
        int i, j = 0;

        for (i = 0; i < (int)old->nr; i++) {
                if (old->ips[i] >= PERF_CONTEXT_MAX)
                        continue;

                new->ips[j].ip = old->ips[i];
                new->ips[j].ms = syms[i];
                j++;
        }

        new->nr = j;
}


int callchain_append(struct callchain_root *root, struct ip_callchain *chain,
                     struct map_symbol *syms, u64 period)
{
        struct resolved_chain *filtered;

        if (!chain->nr)
                return 0;

        filtered = zalloc(sizeof(*filtered) +
                          chain->nr * sizeof(struct resolved_ip));
        if (!filtered)
                return -ENOMEM;

        filter_context(chain, filtered, syms);

        if (!filtered->nr)
                goto end;

        append_chain_children(&root->node, filtered, 0, period);

        if (filtered->nr > root->max_depth)
                root->max_depth = filtered->nr;
end:
        free(filtered);

        return 0;
}

static int
merge_chain_branch(struct callchain_node *dst, struct callchain_node *src,
                   struct resolved_chain *chain)
{
        struct callchain_node *child, *next_child;
        struct callchain_list *list, *next_list;
        int old_pos = chain->nr;
        int err = 0;

        list_for_each_entry_safe(list, next_list, &src->val, list) {
                chain->ips[chain->nr].ip = list->ip;
                chain->ips[chain->nr].ms = list->ms;
                chain->nr++;
                list_del(&list->list);
                free(list);
        }

        if (src->hit)
                append_chain_children(dst, chain, 0, src->hit);

        chain_for_each_child_safe(child, next_child, src) {
                err = merge_chain_branch(dst, child, chain);
                if (err)
                        break;

                list_del(&child->brothers);
                free(child);
        }

        chain->nr = old_pos;

        return err;
}

int callchain_merge(struct callchain_root *dst, struct callchain_root *src)
{
        struct resolved_chain *chain;
        int err;

        chain = malloc(sizeof(*chain) +
                       src->max_depth * sizeof(struct resolved_ip));
        if (!chain)
                return -ENOMEM;

        chain->nr = 0;

        err = merge_chain_branch(&dst->node, &src->node, chain);

        free(chain);

        return err;
}