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authorUlrich Drepper <drepper@redhat.com>2001-03-03 18:21:04 +0000
committerUlrich Drepper <drepper@redhat.com>2001-03-03 18:21:04 +0000
commit2ace57217028da99fc98f79ae0a625a1ec842724 (patch)
treee7d7c34d61fae3e134dcb1029dfd901cae2c2ddc /resolv/gai_misc.c
parent28b20578c97c8d53cc339446fdab31818cf701f6 (diff)
downloadglibc-2ace57217028da99fc98f79ae0a625a1ec842724.tar.gz
Update.
* Versions.def: Add libanl definition. * shlig-versions: Add entry for libanl. * resolv/Makefile (distribute): Add gai_misc.h and ga_test.c. (routines): Add gai_sigqueue. (extra-libs): Add libanl. (libanl-routines): New variable. Add rules to build libanl and ga_test. * resolv/Versions [libc] (GLIBC_2.2.3): Add __gai_sigqueue. [libanl]: New library. * resolv/netdb.h: Add definitions for libanl. * resolv/getaddrinfo_a.c: New file. * resolv/gai_cancel.c: New file. * resolv/gai_error.c: New file. * resolv/gai_misc.c: New file. * resolv/gai_misc.h: New file. * resolv/gai_notify.c: New file. * resolv/gai_suspend.c: New file. * resolv/ga_test.c: New file. * sysdeps/generic/gai_sigqueue.c: New file. * sysdeps/unix/sysv/linux/gai_sigqueue.c: New file. * sysdeps/generic/bits/siginfo.h: Allow __need_sigevent_t being defined and provide only that definition. * sysdeps/unix/sysv/linux/alpha/bits/siginfo.h: Likewise. * sysdeps/unix/sysv/linux/bits/siginfo.h: Likewise. * sysdeps/unix/sysv/linux/ia64/bits/siginfo.h: Likewise. * sysdeps/unix/sysv/linux/mips/bits/siginfo.h: Likewise. * sysdeps/unix/sysv/linux/sparc/bits/siginfo.h: Likewise. * sysdeps/unix/sysv/linux/sparc/sparc64/bits/siginfo.h: Likewise. * rt/aio_misc.c: Fix typos in comments. * rt/lio_listio.c: Pretty printing. Little optimization in request list handling. * elf/rtld.c: Remove commented out code.
Diffstat (limited to 'resolv/gai_misc.c')
-rw-r--r--resolv/gai_misc.c423
1 files changed, 423 insertions, 0 deletions
diff --git a/resolv/gai_misc.c b/resolv/gai_misc.c
new file mode 100644
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+++ b/resolv/gai_misc.c
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+/* Copyright (C) 2001 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@redhat.com>, 2001.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Library General Public License as
+ published by the Free Software Foundation; either version 2 of the
+ License, or (at your option) any later version.
+
+ The GNU C 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
+ Library General Public License for more details.
+
+ You should have received a copy of the GNU Library General Public
+ License along with the GNU C Library; see the file COPYING.LIB. If not,
+ write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+#include <assert.h>
+#include <errno.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <sys/time.h>
+
+#include "gai_misc.h"
+
+
+
+/* Pool of request list entries. */
+static struct requestlist **pool;
+
+/* Number of total and allocated pool entries. */
+static size_t pool_max_size;
+static size_t pool_size;
+
+/* We implement a two dimensional array but allocate each row separately.
+ The macro below determines how many entries should be used per row.
+ It should better be a power of two. */
+#define ENTRIES_PER_ROW 32
+
+/* How many rows we allocate at once. */
+#define ROWS_STEP 8
+
+/* List of available entries. */
+static struct requestlist *freelist;
+
+/* Structure list of all currently processed requests. */
+static struct requestlist *requests;
+static struct requestlist *requests_tail;
+
+/* Number of threads currently running. */
+static int nthreads;
+
+/* Number of threads waiting for work to arrive. */
+static int idle_thread_count;
+
+
+/* These are the values used for optimization. We will probably
+ create a funcion to set these values. */
+static struct gaiinit optim =
+{
+ 20, /* int gai_threads; Maximal number of threads. */
+ 64, /* int gai_num; Number of expected simultanious requests. */
+ 0,
+ 0,
+ 0,
+ 0,
+ 1,
+ 0
+};
+
+
+/* Since the list is global we need a mutex protecting it. */
+pthread_mutex_t __gai_requests_mutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
+
+/* When you add a request to the list and there are idle threads present,
+ you signal this condition variable. When a thread finishes work, it waits
+ on this condition variable for a time before it actually exits. */
+pthread_cond_t __gai_new_request_notification = PTHREAD_COND_INITIALIZER;
+
+
+/* Functions to handle request list pool. */
+static struct requestlist *
+get_elem (void)
+{
+ struct requestlist *result;
+
+ if (freelist == NULL)
+ {
+ struct requestlist *new_row;
+ int cnt;
+
+ if (pool_size + 1 >= pool_max_size)
+ {
+ size_t new_max_size = pool_max_size + ROWS_STEP;
+ struct requestlist **new_tab;
+
+ new_tab = (struct requestlist **)
+ realloc (pool, new_max_size * sizeof (struct requestlist *));
+
+ if (new_tab == NULL)
+ return NULL;
+
+ pool_max_size = new_max_size;
+ pool = new_tab;
+ }
+
+ /* Allocate the new row. */
+ cnt = pool_size == 0 ? optim.gai_num : ENTRIES_PER_ROW;
+ new_row = (struct requestlist *) calloc (cnt,
+ sizeof (struct requestlist));
+ if (new_row == NULL)
+ return NULL;
+
+ pool[pool_size++] = new_row;
+
+ /* Put all the new entries in the freelist. */
+ do
+ {
+ new_row->next = freelist;
+ freelist = new_row++;
+ }
+ while (--cnt > 0);
+ }
+
+ result = freelist;
+ freelist = freelist->next;
+
+ return result;
+}
+
+
+struct requestlist *
+internal_function
+__gai_find_request (const struct gaicb *gaicbp)
+{
+ struct requestlist *runp;
+
+ runp = requests;
+ while (runp != NULL)
+ if (runp->gaicbp == gaicbp)
+ return runp;
+ else
+ runp = runp->next;
+
+ return NULL;
+}
+
+
+int
+internal_function
+__gai_remove_request (struct gaicb *gaicbp)
+{
+ struct requestlist *runp;
+ struct requestlist *lastp;
+
+ runp = requests;
+ lastp = NULL;
+ while (runp != NULL)
+ if (runp->gaicbp == gaicbp)
+ break;
+ else
+ {
+ lastp = runp;
+ runp = runp->next;
+ }
+
+ if (runp == NULL)
+ /* Not known. */
+ return -1;
+ if (runp->running != 0)
+ /* Currently handled. */
+ return 1;
+
+ /* Dequeue the request. */
+ if (lastp == NULL)
+ requests = runp->next;
+ else
+ lastp->next = runp->next;
+ if (runp == requests_tail)
+ requests_tail = lastp;
+
+ return 0;
+}
+
+
+/* The thread handler. */
+static void *handle_requests (void *arg);
+
+
+/* The main function of the async I/O handling. It enqueues requests
+ and if necessary starts and handles threads. */
+struct requestlist *
+internal_function
+__gai_enqueue_request (struct gaicb *gaicbp)
+{
+ struct requestlist *newp;
+ struct requestlist *lastp;
+
+ /* Get the mutex. */
+ pthread_mutex_lock (&__gai_requests_mutex);
+
+ /* Get a new element for the waiting list. */
+ newp = get_elem ();
+ if (newp == NULL)
+ {
+ pthread_mutex_unlock (&__gai_requests_mutex);
+ __set_errno (EAGAIN);
+ return NULL;
+ }
+ newp->running = 0;
+ newp->gaicbp = gaicbp;
+ newp->waiting = NULL;
+ newp->next = NULL;
+
+ lastp = requests_tail;
+ if (requests_tail == NULL)
+ requests = requests_tail = newp;
+ else
+ {
+ requests_tail->next = newp;
+ requests_tail = newp;
+ }
+
+ gaicbp->__return = EAI_INPROGRESS;
+
+ /* See if we need to and are able to create a thread. */
+ if (nthreads < optim.gai_threads && idle_thread_count == 0)
+ {
+ pthread_t thid;
+ pthread_attr_t attr;
+
+ newp->running = 1;
+
+ /* Make sure the thread is created detached. */
+ pthread_attr_init (&attr);
+ pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
+
+ /* Now try to start a thread. */
+ if (pthread_create (&thid, &attr, handle_requests, newp) == 0)
+ /* We managed to enqueue the request. All errors which can
+ happen now can be recognized by calls to `gai_error'. */
+ ++nthreads;
+ else
+ {
+ if (nthreads == 0)
+ {
+ /* We cannot create a thread in the moment and there is
+ also no thread running. This is a problem. `errno' is
+ set to EAGAIN if this is only a temporary problem. */
+ assert (lastp->next == newp);
+ lastp->next = NULL;
+ requests_tail = lastp;
+
+ newp->next = freelist;
+ freelist = newp;
+
+ newp = NULL;
+ }
+ else
+ /* We are not handling the request after all. */
+ newp->running = 0;
+ }
+ }
+
+ /* Enqueue the request in the request queue. */
+ if (newp != NULL)
+ {
+ /* If there is a thread waiting for work, then let it know that we
+ have just given it something to do. */
+ if (idle_thread_count > 0)
+ pthread_cond_signal (&__gai_new_request_notification);
+ }
+
+ /* Release the mutex. */
+ pthread_mutex_unlock (&__gai_requests_mutex);
+
+ return newp;
+}
+
+
+static void *
+handle_requests (void *arg)
+{
+ struct requestlist *runp = (struct requestlist *) arg;
+
+ do
+ {
+ /* If runp is NULL, then we were created to service the work queue
+ in general, not to handle any particular request. In that case we
+ skip the "do work" stuff on the first pass, and go directly to the
+ "get work off the work queue" part of this loop, which is near the
+ end. */
+ if (runp == NULL)
+ pthread_mutex_lock (&__gai_requests_mutex);
+ else
+ {
+ /* Make the request. */
+ struct gaicb *req = runp->gaicbp;
+ struct requestlist *srchp;
+ struct requestlist *lastp;
+
+ req->__return = getaddrinfo (req->ar_name, req->ar_service,
+ req->ar_request, &req->ar_result);
+
+ /* Get the mutex. */
+ pthread_mutex_lock (&__gai_requests_mutex);
+
+ /* Send the signal to notify about finished processing of the
+ request. */
+ __gai_notify (runp);
+
+ /* Now dequeue the current request. */
+ lastp = NULL;
+ srchp = requests;
+ while (srchp != runp)
+ {
+ lastp = srchp;
+ srchp = srchp->next;
+ }
+ assert (runp->running == 1);
+
+ if (requests_tail == runp)
+ requests_tail = lastp;
+ if (lastp == NULL)
+ requests = requests->next;
+ else
+ lastp->next = runp->next;
+
+ /* Free the old element. */
+ runp->next = freelist;
+ freelist = runp;
+ }
+
+ runp = requests;
+ while (runp != NULL && runp->running != 0)
+ runp = runp->next;
+
+ /* If the runlist is empty, then we sleep for a while, waiting for
+ something to arrive in it. */
+ if (runp == NULL && optim.gai_idle_time >= 0)
+ {
+ struct timeval now;
+ struct timespec wakeup_time;
+
+ ++idle_thread_count;
+ gettimeofday (&now, NULL);
+ wakeup_time.tv_sec = now.tv_sec + optim.gai_idle_time;
+ wakeup_time.tv_nsec = now.tv_usec * 1000;
+ if (wakeup_time.tv_nsec > 1000000000)
+ {
+ wakeup_time.tv_nsec -= 1000000000;
+ ++wakeup_time.tv_sec;
+ }
+ pthread_cond_timedwait (&__gai_new_request_notification,
+ &__gai_requests_mutex, &wakeup_time);
+ --idle_thread_count;
+ runp = requests;
+ while (runp != NULL && runp->running != 0)
+ runp = runp->next;
+ }
+
+ if (runp == NULL)
+ --nthreads;
+ else
+ {
+ /* Mark the request as being worked on. */
+ assert (runp->running == 0);
+ runp->running = 1;
+
+ /* If we have a request to process, and there's still another in
+ the run list, then we need to either wake up or create a new
+ thread to service the request that is still in the run list. */
+ if (requests != NULL)
+ {
+ /* There are at least two items in the work queue to work on.
+ If there are other idle threads, then we should wake them
+ up for these other work elements; otherwise, we should try
+ to create a new thread. */
+ if (idle_thread_count > 0)
+ pthread_cond_signal (&__gai_new_request_notification);
+ else if (nthreads < optim.gai_threads)
+ {
+ pthread_t thid;
+ pthread_attr_t attr;
+
+ /* Make sure the thread is created detached. */
+ pthread_attr_init (&attr);
+ pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
+
+ /* Now try to start a thread. If we fail, no big deal,
+ because we know that there is at least one thread (us)
+ that is working on lookup operations. */
+ if (pthread_create (&thid, &attr, handle_requests, NULL)
+ == 0)
+ ++nthreads;
+ }
+ }
+ }
+
+ /* Release the mutex. */
+ pthread_mutex_unlock (&__gai_requests_mutex);
+ }
+ while (runp != NULL);
+
+ pthread_exit (NULL);
+}
+
+
+/* Free allocated resources. */
+static void
+__attribute__ ((unused))
+free_res (void)
+{
+ size_t row;
+
+ for (row = 0; row < pool_max_size; ++row)
+ free (pool[row]);
+
+ free (pool);
+}
+text_set_element (__libc_subfreeres, free_res);