/*
 * Copyright (C) 2009-2011, 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"

__thread struct callchain_cursor callchain_cursor;

bool ip_callchain__valid(struct ip_callchain *chain,
                         const union perf_event *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, siblings)

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

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 = callchain_cumul_hits(chain);

        while (*p) {
                u64 rnode_cumul;

                parent = *p;
                rnode = rb_entry(parent, struct callchain_node, rb_node);
                rnode_cumul = callchain_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 __maybe_unused)
{
        __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 (callchain_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 __maybe_unused)
{
        __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 (callchain_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 __maybe_unused, 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 callchain_register_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->siblings, &parent->children);

        return new;
}


/*
 * Fill the node with callchain values
 */
static void
fill_node(struct callchain_node *node, struct callchain_cursor *cursor)
{
        struct callchain_cursor_node *cursor_node;

        node->val_nr = cursor->nr - cursor->pos;
        if (!node->val_nr)
                pr_warning("Warning: empty node in callchain tree\n");

        cursor_node = callchain_cursor_current(cursor);

        while (cursor_node) {
                struct callchain_list *call;

                call = zalloc(sizeof(*call));
                if (!call) {
                        perror("not enough memory for the code path tree");
                        return;
                }
                call->ip = cursor_node->ip;
                call->ms.sym = cursor_node->sym;
                call->ms.map = cursor_node->map;
                list_add_tail(&call->list, &node->val);

                callchain_cursor_advance(cursor);
                cursor_node = callchain_cursor_current(cursor);
        }
}

static void
add_child(struct callchain_node *parent,
          struct callchain_cursor *cursor,
          u64 period)
{
        struct callchain_node *new;

        new = create_child(parent, false);
        fill_node(new, cursor);

        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 callchain_cursor *cursor,
                struct callchain_list *to_split,
                u64 idx_parents, u64 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 = callchain_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 < cursor->nr) {
                parent->hit = 0;
                add_child(parent, cursor, period);
                parent->children_hit += period;
        } else {
                parent->hit = period;
        }
}

static int
append_chain(struct callchain_node *root,
             struct callchain_cursor *cursor,
             u64 period);

static void
append_chain_children(struct callchain_node *root,
                      struct callchain_cursor *cursor,
                      u64 period)
{
        struct callchain_node *rnode;

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

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

inc_children_hit:
        root->children_hit += period;
}

static int
append_chain(struct callchain_node *root,
             struct callchain_cursor *cursor,
             u64 period)
{
        struct callchain_cursor_node *curr_snap = cursor->curr;
        struct callchain_list *cnode;
        u64 start = cursor->pos;
        bool found = false;
        u64 matches;

        /*
         * 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 callchain_cursor_node *node;
                struct symbol *sym;

                node = callchain_cursor_current(cursor);
                if (!node)
                        break;

                sym = node->sym;

                if (cnode->ms.sym && sym) {
                        if (cnode->ms.sym->start != sym->start)
                                break;
                } else if (cnode->ip != node->ip)
                        break;

                if (!found)
                        found = true;

                callchain_cursor_advance(cursor);
        }

        /* matches not, relay on the parent */
        if (!found) {
                cursor->curr = curr_snap;
                cursor->pos = start;
                return -1;
        }

        matches = cursor->pos - start;

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

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

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

        return 0;
}

int callchain_append(struct callchain_root *root,
                     struct callchain_cursor *cursor,
                     u64 period)
{
        if (!cursor->nr)
                return 0;

        callchain_cursor_commit(cursor);

        append_chain_children(&root->node, cursor, period);

        if (cursor->nr > root->max_depth)
                root->max_depth = cursor->nr;

        return 0;
}

static int
merge_chain_branch(struct callchain_cursor *cursor,
                   struct callchain_node *dst, struct callchain_node *src)
{
        struct callchain_cursor_node **old_last = cursor->last;
        struct callchain_node *child, *next_child;
        struct callchain_list *list, *next_list;
        int old_pos = cursor->nr;
        int err = 0;

        list_for_each_entry_safe(list, next_list, &src->val, list) {
                callchain_cursor_append(cursor, list->ip,
                                        list->ms.map, list->ms.sym);
                list_del(&list->list);
                free(list);
        }

        if (src->hit) {
                callchain_cursor_commit(cursor);
                append_chain_children(dst, cursor, src->hit);
        }

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

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

        cursor->nr = old_pos;
        cursor->last = old_last;

        return err;
}

int callchain_merge(struct callchain_cursor *cursor,
                    struct callchain_root *dst, struct callchain_root *src)
{
        return merge_chain_branch(cursor, &dst->node, &src->node);
}

int callchain_cursor_append(struct callchain_cursor *cursor,
                            u64 ip, struct map *map, struct symbol *sym)
{
        struct callchain_cursor_node *node = *cursor->last;

        if (!node) {
                node = calloc(1, sizeof(*node));
                if (!node)
                        return -ENOMEM;

                *cursor->last = node;
        }

        node->ip = ip;
        node->map = map;
        node->sym = sym;

        cursor->nr++;

        cursor->last = &node->next;

        return 0;
}