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libwebsockets/lib/plat/unix/unix-init.c

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/*
* libwebsockets - small server side websockets and web server implementation
*
* Copyright (C) 2010-2018 Andy Green <andy@warmcat.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation:
* version 2.1 of the License.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301 USA
*/
#define _GNU_SOURCE
#include "core/private.h"
#include <pwd.h>
#include <grp.h>
#ifdef LWS_WITH_PLUGINS
#include <dlfcn.h>
#endif
#include <dirent.h>
#if defined(LWS_WITH_NETWORK)
static void
lws_sul_plat_unix(lws_sorted_usec_list_t *sul)
{
struct lws_context_per_thread *pt =
lws_container_of(sul, struct lws_context_per_thread, sul_plat);
struct lws_context *context = pt->context;
#if defined(LWS_ROLE_CGI) || defined(LWS_ROLE_DBUS)
time_t now = time(NULL);
#endif
#if !defined(LWS_NO_DAEMONIZE)
/* if our parent went down, don't linger around */
if (pt->context->started_with_parent &&
kill(pt->context->started_with_parent, 0) < 0)
kill(getpid(), SIGTERM);
#endif
if (pt->context->deprecated && !pt->context->count_wsi_allocated) {
lwsl_notice("%s: ending deprecated context\n", __func__);
kill(getpid(), SIGINT);
return;
}
lws_check_deferred_free(context, 0, 0);
lws_context_lock(context, "periodic checks");
lws_start_foreach_llp(struct lws_vhost **, pv,
context->no_listener_vhost_list) {
struct lws_vhost *v = *pv;
lwsl_debug("deferred iface: checking if on vh %s\n", (*pv)->name);
if (_lws_vhost_init_server(NULL, *pv) == 0) {
/* became happy */
lwsl_notice("vh %s: became connected\n", v->name);
*pv = v->no_listener_vhost_list;
v->no_listener_vhost_list = NULL;
break;
}
} lws_end_foreach_llp(pv, no_listener_vhost_list);
lws_context_unlock(context);
#if defined(LWS_ROLE_CGI)
role_ops_cgi.periodic_checks(context, 0, now);
#endif
#if defined(LWS_ROLE_DBUS)
role_ops_dbus.periodic_checks(context, 0, now);
#endif
__lws_sul_insert(&pt->pt_sul_owner, &pt->sul_plat, 30 * LWS_US_PER_SEC);
}
#endif
int
lws_plat_init(struct lws_context *context,
const struct lws_context_creation_info *info)
{
int fd;
#if defined(LWS_WITH_NETWORK)
unix plat: add minimal wsi fd map option An lws context usually contains a processwide fd -> wsi lookup table. This allows any possible fd returned by a *nix type OS to be immediately converted to a wsi just by indexing an array of struct lws * the size of the highest possible fd, as found by ulimit -n or similar. This works modestly for Linux type systems where the default ulimit -n for a process is 1024, it means a 4KB or 8KB lookup table for 32-bit or 64-bit systems. However in the case your lws usage is much simpler, like one outgoing client connection and no serving, this represents increasing waste. It's made much worse if the system has a much larger default ulimit -n, eg 1M, the table is occupying 4MB or 8MB, of which you will only use one. Even so, because lws can't be sure the OS won't return a socket fd at any number up to (ulimit -n - 1), it has to allocate the whole lookup table at the moment. This patch looks to see if the context creation info is setting info->fd_limit_per_thread... if it leaves it at the default 0, then everything is as it was before this patch. However if finds that (info->fd_limit_per_thread * actual_number_of_service_threads) where the default number of service threads is 1, is less than the fd limit set by ulimit -n, lws switches to a slower lookup table scheme, which only allocates the requested number of slots. Lookups happen then by iterating the table and comparing rather than indexing the array directly, which is obviously somewhat of a performance hit. However in the case where you know lws will only have a very few wsi maximum, this method can very usefully trade off speed to be able to avoid the allocation sized by ulimit -n. minimal examples for client that can make use of this are also modified by this patch to use the smaller context allocations.
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/*
* master context has the process-global fd lookup array. This can be
* done two different ways now; one or the other is done depending on if
* info->fd_limit_per_thread was snonzero
*
* - default: allocate a worst-case lookup array sized for ulimit -n
* and use the fd directly as an index into it
*
* - slow: allocate context->max_fds entries only (which can be
* forced at context creation time to be
* info->fd_limit_per_thread * the number of threads)
* and search the array to lookup fds
*
* the default way is optimized for server, if you only use one or two
* client wsi the slow way may save a lot of memory.
*
* Both ways allocate an array of struct lws *... one allocates it for
* all possible fd indexes the process could produce and uses it as a
* map, the other allocates for an amount of wsi the lws context is
* expected to use and searches through it to manipulate it.
*/
context->lws_lookup = lws_zalloc(sizeof(struct lws *) *
context->max_fds, "lws_lookup");
unix plat: add minimal wsi fd map option An lws context usually contains a processwide fd -> wsi lookup table. This allows any possible fd returned by a *nix type OS to be immediately converted to a wsi just by indexing an array of struct lws * the size of the highest possible fd, as found by ulimit -n or similar. This works modestly for Linux type systems where the default ulimit -n for a process is 1024, it means a 4KB or 8KB lookup table for 32-bit or 64-bit systems. However in the case your lws usage is much simpler, like one outgoing client connection and no serving, this represents increasing waste. It's made much worse if the system has a much larger default ulimit -n, eg 1M, the table is occupying 4MB or 8MB, of which you will only use one. Even so, because lws can't be sure the OS won't return a socket fd at any number up to (ulimit -n - 1), it has to allocate the whole lookup table at the moment. This patch looks to see if the context creation info is setting info->fd_limit_per_thread... if it leaves it at the default 0, then everything is as it was before this patch. However if finds that (info->fd_limit_per_thread * actual_number_of_service_threads) where the default number of service threads is 1, is less than the fd limit set by ulimit -n, lws switches to a slower lookup table scheme, which only allocates the requested number of slots. Lookups happen then by iterating the table and comparing rather than indexing the array directly, which is obviously somewhat of a performance hit. However in the case where you know lws will only have a very few wsi maximum, this method can very usefully trade off speed to be able to avoid the allocation sized by ulimit -n. minimal examples for client that can make use of this are also modified by this patch to use the smaller context allocations.
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if (!context->lws_lookup) {
lwsl_err("%s: OOM on alloc lws_lookup array for %d conn\n",
__func__, context->max_fds);
return 1;
}
unix plat: add minimal wsi fd map option An lws context usually contains a processwide fd -> wsi lookup table. This allows any possible fd returned by a *nix type OS to be immediately converted to a wsi just by indexing an array of struct lws * the size of the highest possible fd, as found by ulimit -n or similar. This works modestly for Linux type systems where the default ulimit -n for a process is 1024, it means a 4KB or 8KB lookup table for 32-bit or 64-bit systems. However in the case your lws usage is much simpler, like one outgoing client connection and no serving, this represents increasing waste. It's made much worse if the system has a much larger default ulimit -n, eg 1M, the table is occupying 4MB or 8MB, of which you will only use one. Even so, because lws can't be sure the OS won't return a socket fd at any number up to (ulimit -n - 1), it has to allocate the whole lookup table at the moment. This patch looks to see if the context creation info is setting info->fd_limit_per_thread... if it leaves it at the default 0, then everything is as it was before this patch. However if finds that (info->fd_limit_per_thread * actual_number_of_service_threads) where the default number of service threads is 1, is less than the fd limit set by ulimit -n, lws switches to a slower lookup table scheme, which only allocates the requested number of slots. Lookups happen then by iterating the table and comparing rather than indexing the array directly, which is obviously somewhat of a performance hit. However in the case where you know lws will only have a very few wsi maximum, this method can very usefully trade off speed to be able to avoid the allocation sized by ulimit -n. minimal examples for client that can make use of this are also modified by this patch to use the smaller context allocations.
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lwsl_info(" mem: platform fd map: %5lu B\n",
(unsigned long)(sizeof(struct lws *) * context->max_fds));
#endif
fd = lws_open(SYSTEM_RANDOM_FILEPATH, O_RDONLY);
context->fd_random = fd;
if (context->fd_random < 0) {
lwsl_err("Unable to open random device %s %d\n",
SYSTEM_RANDOM_FILEPATH, context->fd_random);
return 1;
}
#if defined(LWS_WITH_PLUGINS)
if (info->plugin_dirs)
lws_plat_plugins_init(context, info->plugin_dirs);
#endif
#if defined(LWS_WITH_NETWORK)
/* we only need to do this on pt[0] */
context->pt[0].sul_plat.cb = lws_sul_plat_unix;
__lws_sul_insert(&context->pt[0].pt_sul_owner, &context->pt[0].sul_plat,
30 * LWS_US_PER_SEC);
#endif
return 0;
}
int
lws_plat_context_early_init(void)
{
#if !defined(LWS_AVOID_SIGPIPE_IGN)
signal(SIGPIPE, SIG_IGN);
#endif
return 0;
}
void
lws_plat_context_early_destroy(struct lws_context *context)
{
}
void
lws_plat_context_late_destroy(struct lws_context *context)
{
#ifdef LWS_WITH_PLUGINS
if (context->plugin_list)
lws_plat_plugins_destroy(context);
#endif
#if defined(LWS_WITH_NETWORK)
if (context->lws_lookup)
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lws_free_set_NULL(context->lws_lookup);
#endif
if (!context->fd_random)
lwsl_err("ZERO RANDOM FD\n");
if (context->fd_random != LWS_INVALID_FILE)
close(context->fd_random);
}