Clean-up: modernize pretty_xml.cpp

[lttng-tools.git] / src / common / futex.c

diff --git a/src/common/futex.c b/src/common/futex.c
deleted file mode 100644 (file)
index f1b33ea..0000000
--- a/src/common/futex.c
+++ /dev/null
@@ -1,152 +0,0 @@
-/*
- * Copyright (C)  2011 - David Goulet <david.goulet@polymtl.ca>
- *                       Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License, version 2 only,
- * as published by the Free Software Foundation.
- *
- * This program 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 General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
-
-#define _LGPL_SOURCE
-#include <limits.h>
-#include <unistd.h>
-#include <urcu.h>
-#include <urcu/futex.h>
-
-#include <common/common.h>
-
-#include "futex.h"
-
-/*
- * This futex wait/wake scheme only works for N wakers / 1 waiters. Hence the
- * "nto1" added to all function signature.
- *
- * The code is adapted from the adaptative busy wait/wake_up scheme used in
- * liburcu.
- */
-
-/* Number of busy-loop attempts before waiting on futex. */
-#define FUTEX_WAIT_ATTEMPTS 1000
-
-enum futex_wait_state {
-       /* FUTEX_WAIT_WAITING is compared directly (futex() compares it). */
-       FUTEX_WAIT_WAITING =    0,
-       /* non-zero are used as masks. */
-       FUTEX_WAIT_WAKEUP =     (1 << 0),
-       FUTEX_WAIT_RUNNING =    (1 << 1),
-       FUTEX_WAIT_TEARDOWN =   (1 << 2),
-};
-
-/*
- * Update futex according to active or not. This scheme is used to wake every
- * libust waiting on the shared memory map futex hence the INT_MAX used in the
- * futex() call. If active, we set the value and wake everyone else we indicate
- * that we are gone (cleanup() case).
- */
-LTTNG_HIDDEN
-void futex_wait_update(int32_t *futex, int active)
-{
-       if (active) {
-               uatomic_set(futex, 1);
-               if (futex_async(futex, FUTEX_WAKE,
-                               INT_MAX, NULL, NULL, 0) < 0) {
-                       PERROR("futex_async");
-                       abort();
-               }
-       } else {
-               uatomic_set(futex, 0);
-       }
-
-       DBG("Futex wait update active %d", active);
-}
-
-/*
- * Prepare futex.
- */
-LTTNG_HIDDEN
-void futex_nto1_prepare(int32_t *futex)
-{
-       uatomic_set(futex, FUTEX_WAIT_WAITING);
-       cmm_smp_mb();
-
-       DBG("Futex n to 1 prepare done");
-}
-
-/*
- * Wait futex.
- */
-LTTNG_HIDDEN
-void futex_nto1_wait(int32_t *futex)
-{
-       unsigned int i;
-
-       /* Load and test condition before read state */
-       cmm_smp_rmb();
-       for (i = 0; i < FUTEX_WAIT_ATTEMPTS; i++) {
-               if (uatomic_read(futex) != FUTEX_WAIT_WAITING)
-                       goto skip_futex_wait;
-               caa_cpu_relax();
-       }
-       while (futex_noasync(futex, FUTEX_WAIT, FUTEX_WAIT_WAITING,
-                       NULL, NULL, 0)) {
-               switch (errno) {
-               case EWOULDBLOCK:
-                       /* Value already changed. */
-                       goto skip_futex_wait;
-               case EINTR:
-                       /* Retry if interrupted by signal. */
-                       break;  /* Get out of switch. */
-               default:
-                       /* Unexpected error. */
-                       PERROR("futex");
-                       abort();
-               }
-       }
-skip_futex_wait:
-
-       /* Tell waker thread than we are running. */
-       uatomic_or(futex, FUTEX_WAIT_RUNNING);
-
-       /*
-        * Wait until waker thread lets us know it's ok to tear down
-        * memory allocated for the futex.
-        */
-       for (i = 0; i < FUTEX_WAIT_ATTEMPTS; i++) {
-               if (uatomic_read(futex) & FUTEX_WAIT_TEARDOWN)
-                       break;
-               caa_cpu_relax();
-       }
-       while (!(uatomic_read(futex) & FUTEX_WAIT_TEARDOWN))
-               poll(NULL, 0, 10);
-       assert(uatomic_read(futex) & FUTEX_WAIT_TEARDOWN);
-       DBG("Futex n to 1 wait done");
-}
-
-/*
- * Wake 1 futex.
- */
-LTTNG_HIDDEN
-void futex_nto1_wake(int32_t *futex)
-{
-       cmm_smp_mb();
-       uatomic_set(futex, FUTEX_WAIT_WAKEUP);
-       if (!(uatomic_read(futex) & FUTEX_WAIT_RUNNING)) {
-               if (futex_noasync(futex, FUTEX_WAKE, 1,
-                               NULL, NULL, 0) < 0) {
-                       PERROR("futex_noasync");
-                       abort();
-               }
-       }
-       /* Allow teardown of futex. */
-       uatomic_or(futex, FUTEX_WAIT_TEARDOWN);
-       DBG("Futex n to 1 wake done");
-}