/* Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You under the Apache License, Version 2.0

 * (the "License"); you may not use this file except in compliance with

 * the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#include <assert.h>

#include <stddef.h>

#include <stdlib.h>

#include <apr_thread_mutex.h>

#include <apr_thread_cond.h>

#include <apr_strings.h>

#include <apr_time.h>

#include <httpd.h>

#include <http_core.h>

#include <http_log.h>

#include "mod_http2.h"

#include "h2_private.h"

#include "h2.h"

#include "h2_config.h"

#include "h2_conn.h"

#include "h2_ctx.h"

#include "h2_h2.h"

#include "h2_mplx.h"

#include "h2_request.h"

#include "h2_task.h"

#include "h2_util.h"

#include "h2_ngn_shed.h"

typedef struct h2_ngn_entry h2_ngn_entry;

struct h2_ngn_entry {

    APR_RING_ENTRY(h2_ngn_entry) link;

    h2_task *task;

    request_rec *r;

};

#define H2_NGN_ENTRY_NEXT(e)	APR_RING_NEXT((e), link)

#define H2_NGN_ENTRY_PREV(e)	APR_RING_PREV((e), link)

#define H2_NGN_ENTRY_REMOVE(e)	APR_RING_REMOVE((e), link)

#define H2_REQ_ENTRIES_SENTINEL(b)	APR_RING_SENTINEL((b), h2_ngn_entry, link)

#define H2_REQ_ENTRIES_EMPTY(b)	APR_RING_EMPTY((b), h2_ngn_entry, link)

#define H2_REQ_ENTRIES_FIRST(b)	APR_RING_FIRST(b)

#define H2_REQ_ENTRIES_LAST(b)	APR_RING_LAST(b)

#define H2_REQ_ENTRIES_INSERT_HEAD(b, e) do {				\

h2_ngn_entry *ap__b = (e);                                        \

APR_RING_INSERT_HEAD((b), ap__b, h2_ngn_entry, link);	\

} while (0)

#define H2_REQ_ENTRIES_INSERT_TAIL(b, e) do {				\

h2_ngn_entry *ap__b = (e);					\

APR_RING_INSERT_TAIL((b), ap__b, h2_ngn_entry, link);	\

} while (0)

struct h2_req_engine {

    const char *id;        /* identifier */

    const char *type;      /* name of the engine type */

    apr_pool_t *pool;      /* pool for engine specific allocations */

    conn_rec *c;           /* connection this engine is assigned to */

    h2_task *task;         /* the task this engine is based on, running in */

    h2_ngn_shed *shed;

    unsigned int shutdown : 1; /* engine is being shut down */

    unsigned int done : 1;     /* engine has finished */

    APR_RING_HEAD(h2_req_entries, h2_ngn_entry) entries;

    int capacity;     /* maximum concurrent requests */

    int no_assigned;  /* # of assigned requests */

    int no_live;      /* # of live */

    int no_finished;  /* # of finished */

    h2_output_consumed *out_consumed;

    void *out_consumed_ctx;

};

const char *h2_req_engine_get_id(h2_req_engine *engine)

{

    return engine->id;

}

int h2_req_engine_is_shutdown(h2_req_engine *engine)

{

    return engine->shutdown;

}

void h2_req_engine_out_consumed(h2_req_engine *engine, conn_rec *c, 

                                apr_off_t bytes)

{

    if (engine->out_consumed) {

        engine->out_consumed(engine->out_consumed_ctx, c, bytes);

    }

}

h2_ngn_shed *h2_ngn_shed_create(apr_pool_t *pool, conn_rec *c,

                                int default_capacity, 

                                apr_size_t req_buffer_size)

{

    h2_ngn_shed *shed;

    shed = apr_pcalloc(pool, sizeof(*shed));

    shed->c = c;

    shed->pool = pool;

    shed->default_capacity = default_capacity;

    shed->req_buffer_size = req_buffer_size;

    shed->ngns = apr_hash_make(pool);

    return shed;

}

void h2_ngn_shed_set_ctx(h2_ngn_shed *shed, void *user_ctx)

{

    shed->user_ctx = user_ctx;

}

void *h2_ngn_shed_get_ctx(h2_ngn_shed *shed)

{

    return shed->user_ctx;

}

h2_ngn_shed *h2_ngn_shed_get_shed(h2_req_engine *ngn)

{

    return ngn->shed;

}

void h2_ngn_shed_abort(h2_ngn_shed *shed)

{

    ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, shed->c, APLOGNO(03394)

                  "h2_ngn_shed(%ld): abort", shed->c->id);

    shed->aborted = 1;

}

static void ngn_add_task(h2_req_engine *ngn, h2_task *task, request_rec *r)

{

    h2_ngn_entry *entry = apr_pcalloc(task->pool, sizeof(*entry));

    APR_RING_ELEM_INIT(entry, link);

    entry->task = task;

    entry->r = r;

    H2_REQ_ENTRIES_INSERT_TAIL(&ngn->entries, entry);

    ngn->no_assigned++;

}

apr_status_t h2_ngn_shed_push_request(h2_ngn_shed *shed, const char *ngn_type, 

                                      request_rec *r, 

                                      http2_req_engine_init *einit) 

{

    h2_req_engine *ngn;

    h2_task *task = h2_ctx_rget_task(r);

    ap_assert(task);

    ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, shed->c,

                  "h2_ngn_shed(%ld): PUSHing request (task=%s)", shed->c->id, 

                  task->id);

    if (task->request->serialize) {

        /* Max compatibility, deny processing of this */

        return APR_EOF;

    }

    if (task->assigned) {

        --task->assigned->no_assigned;

        --task->assigned->no_live;

        task->assigned = NULL;

    }

    if (task->engine) {

        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, task->c, 

                      "h2_ngn_shed(%ld): push task(%s) hosting engine %s " 

                      "already with %d tasks", 

                      shed->c->id, task->id, task->engine->id,

                      task->engine->no_assigned);

        task->assigned = task->engine;

        ngn_add_task(task->engine, task, r);

        return APR_SUCCESS;

    }

    ngn = apr_hash_get(shed->ngns, ngn_type, APR_HASH_KEY_STRING);

    if (ngn && !ngn->shutdown) {

        /* this task will be processed in another thread,

         * freeze any I/O for the time being. */

        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, task->c,

                      "h2_ngn_shed(%ld): pushing request %s to %s", 

                      shed->c->id, task->id, ngn->id);

        if (!h2_task_has_thawed(task)) {

            h2_task_freeze(task);

        }

        ngn_add_task(ngn, task, r);

        return APR_SUCCESS;

    }

    /* no existing engine or being shut down, start a new one */

    if (einit) {

        apr_status_t status;

        apr_pool_t *pool = task->pool;

        h2_req_engine *newngn;

        newngn = apr_pcalloc(pool, sizeof(*ngn));

        newngn->pool = pool;

        newngn->id   = apr_psprintf(pool, "ngn-%s", task->id);

        newngn->type = apr_pstrdup(pool, ngn_type);

        newngn->c    = task->c;

        newngn->shed = shed;

        newngn->capacity = shed->default_capacity;

        newngn->no_assigned = 1;

        newngn->no_live = 1;

        APR_RING_INIT(&newngn->entries, h2_ngn_entry, link);

        status = einit(newngn, newngn->id, newngn->type, newngn->pool,

                       shed->req_buffer_size, r,

                       &newngn->out_consumed, &newngn->out_consumed_ctx);

        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, status, task->c, APLOGNO(03395)

                      "h2_ngn_shed(%ld): create engine %s (%s)", 

                      shed->c->id, newngn->id, newngn->type);

        if (status == APR_SUCCESS) {

            newngn->task = task;

            task->engine = newngn;

            task->assigned = newngn;

            apr_hash_set(shed->ngns, newngn->type, APR_HASH_KEY_STRING, newngn);

        }

        return status;

    }

    return APR_EOF;

}

static h2_ngn_entry *pop_detached(h2_req_engine *ngn)

{

    h2_ngn_entry *entry;

    for (entry = H2_REQ_ENTRIES_FIRST(&ngn->entries);

         entry != H2_REQ_ENTRIES_SENTINEL(&ngn->entries);

         entry = H2_NGN_ENTRY_NEXT(entry)) {

        if (h2_task_has_thawed(entry->task) 

            || (entry->task->engine == ngn)) {

            /* The task hosting this engine can always be pulled by it.

             * For other task, they need to become detached, e.g. no longer

             * assigned to another worker. */

            H2_NGN_ENTRY_REMOVE(entry);

            return entry;

        }

    }

    return NULL;

}

apr_status_t h2_ngn_shed_pull_request(h2_ngn_shed *shed, 

                                      h2_req_engine *ngn, 

                                      int capacity, 

                                      int want_shutdown,

                                      request_rec **pr)

{   

    h2_ngn_entry *entry;

    ap_assert(ngn);

    *pr = NULL;

    ap_log_cerror(APLOG_MARK, APLOG_TRACE3, 0, shed->c, APLOGNO(03396)

                  "h2_ngn_shed(%ld): pull task for engine %s, shutdown=%d", 

                  shed->c->id, ngn->id, want_shutdown);

    if (shed->aborted) {

        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, shed->c, APLOGNO(03397)

                      "h2_ngn_shed(%ld): abort while pulling requests %s", 

                      shed->c->id, ngn->id);

        ngn->shutdown = 1;

        return APR_ECONNABORTED;

    }

    ngn->capacity = capacity;

    if (H2_REQ_ENTRIES_EMPTY(&ngn->entries)) {

        if (want_shutdown) {

            ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, shed->c,

                          "h2_ngn_shed(%ld): emtpy queue, shutdown engine %s", 

                          shed->c->id, ngn->id);

            ngn->shutdown = 1;

        }

        return ngn->shutdown? APR_EOF : APR_EAGAIN;

    }

    if ((entry = pop_detached(ngn))) {

        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, entry->task->c, APLOGNO(03398)

                      "h2_ngn_shed(%ld): pulled request %s for engine %s", 

                      shed->c->id, entry->task->id, ngn->id);

        ngn->no_live++;

        *pr = entry->r;

        entry->task->assigned = ngn;

        /* task will now run in ngn's own thread. Modules like lua

         * seem to require the correct thread set in the conn_rec.

         * See PR 59542. */

        if (entry->task->c && ngn->c) {

            entry->task->c->current_thread = ngn->c->current_thread;

        }

        if (entry->task->engine == ngn) {

            /* If an engine pushes its own base task, and then pulls

             * it back to itself again, it needs to be thawed.

             */

            h2_task_thaw(entry->task);

        }

        return APR_SUCCESS;

    }

    if (1) {

        h2_ngn_entry *entry = H2_REQ_ENTRIES_FIRST(&ngn->entries);

        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, shed->c, APLOGNO(03399)

                      "h2_ngn_shed(%ld): pull task, nothing, first task %s", 

                      shed->c->id, entry->task->id);

    }

    return APR_EAGAIN;

}

static apr_status_t ngn_done_task(h2_ngn_shed *shed, h2_req_engine *ngn, 

                                  h2_task *task, int waslive, int aborted)

{

    ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, shed->c, APLOGNO(03400)

                  "h2_ngn_shed(%ld): task %s %s by %s", 

                  shed->c->id, task->id, aborted? "aborted":"done", ngn->id);

    ngn->no_finished++;

    if (waslive) ngn->no_live--;

    ngn->no_assigned--;

    task->assigned = NULL;

    return APR_SUCCESS;

}

apr_status_t h2_ngn_shed_done_task(h2_ngn_shed *shed, 

                                    struct h2_req_engine *ngn, h2_task *task)

{

    return ngn_done_task(shed, ngn, task, 1, 0);

}

void h2_ngn_shed_done_ngn(h2_ngn_shed *shed, struct h2_req_engine *ngn)

{

    if (ngn->done) {

        return;

    }

    if (!shed->aborted && !H2_REQ_ENTRIES_EMPTY(&ngn->entries)) {

        h2_ngn_entry *entry;

        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, shed->c,

                      "h2_ngn_shed(%ld): exit engine %s (%s), "

                      "has still requests queued, shutdown=%d,"

                      "assigned=%ld, live=%ld, finished=%ld", 

                      shed->c->id, ngn->id, ngn->type,

                      ngn->shutdown, 

                      (long)ngn->no_assigned, (long)ngn->no_live,

                      (long)ngn->no_finished);

        for (entry = H2_REQ_ENTRIES_FIRST(&ngn->entries);

             entry != H2_REQ_ENTRIES_SENTINEL(&ngn->entries);

             entry = H2_NGN_ENTRY_NEXT(entry)) {

            h2_task *task = entry->task;

            ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, shed->c,

                          "h2_ngn_shed(%ld): engine %s has queued task %s, "

                          "frozen=%d, aborting",

                          shed->c->id, ngn->id, task->id, task->frozen);

            ngn_done_task(shed, ngn, task, 0, 1);

            task->engine = task->assigned = NULL;

        }

    }

    if (!shed->aborted && (ngn->no_assigned > 1 || ngn->no_live > 1)) {

        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, shed->c,

                      "h2_ngn_shed(%ld): exit engine %s (%s), "

                      "assigned=%ld, live=%ld, finished=%ld", 

                      shed->c->id, ngn->id, ngn->type,

                      (long)ngn->no_assigned, (long)ngn->no_live,

                      (long)ngn->no_finished);

    }

    else {

        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, shed->c,

                      "h2_ngn_shed(%ld): exit engine %s", 

                      shed->c->id, ngn->id);

    }

    apr_hash_set(shed->ngns, ngn->type, APR_HASH_KEY_STRING, NULL);

    ngn->done = 1;

}

void h2_ngn_shed_destroy(h2_ngn_shed *shed)

{

    ap_assert(apr_hash_count(shed->ngns) == 0);

}