Add "automated" RCU memory reclamation.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
all: checkarch liburcu.so urcu.o \
liburcu-qsbr.so urcu-qsbr.o \
liburcu-mb.so urcu-mb.o \
+ liburcu-reclaim.so urcu-reclaim.o \
urcu-yield.o \
subdirs
urcu-qsbr.o: urcu-qsbr.c urcu-qsbr.h
$(CC) -fPIC ${CFLAGS} $(LDFLAGS) -c -o $@ $(SRC_DEP)
+urcu-reclaim.o: urcu-reclaim.c urcu-reclaim.h
+ $(CC) -fPIC ${CFLAGS} $(LDFLAGS) -c -o $@ $(SRC_DEP)
+
liburcu.so: urcu.o
$(CC) ${LDFLAGS} -fPIC -shared -o $@ $<
liburcu-mb.so: urcu-mb.o
$(CC) ${LDFLAGS} -fPIC -shared -o $@ $<
+liburcu-reclaim.so: urcu-reclaim.o
+ $(CC) ${LDFLAGS} -fPIC -shared -o $@ $<
+
urcu-yield.o: urcu.c urcu.h
$(CC) -DDEBUG_YIELD ${CFLAGS} $(LDFLAGS) -c -o $@ $(SRC_DEP)
URCU_SIGNAL_YIELD=${LIBDIR}/urcu-yield.o ${LIBDIR}/urcu.h
URCU_MB=${LIBDIR}/urcu-mb.o ${LIBDIR}/urcu.h
URCU_QSBR=${LIBDIR}/urcu-qsbr.o ${LIBDIR}/urcu-qsbr.h
+URCU_MB_RECLAIM=${LIBDIR}/urcu-mb.o ${LIBDIR}/urcu-reclaim.o ${LIBDIR}/urcu.h
all: test_urcu test_urcu_dynamic_link test_urcu_timing \
test_rwlock_timing test_rwlock test_perthreadlock_timing \
urcu-asm.S test_qsbr_timing test_qsbr urcu-asm.o urcutorture \
urcutorture-yield test_mutex test_looplen test_urcu_gc \
test_urcu_gc_mb test_qsbr_gc test_qsbr_lgc test_urcu_lgc \
- test_urcu_lgc_mb test_qsbr_dynamic_link
+ test_urcu_lgc_mb test_qsbr_dynamic_link test_urcu_mb_reclaim
api.h: ${APIHEADER}
cp -f ${APIHEADER} api.h
test_urcu_lgc_mb: test_urcu_gc.c ${URCU_MB}
$(CC) -DTEST_LOCAL_GC -DURCU_MB ${CFLAGS} $(LDFLAGS) -o $@ $(SRC_DEP)
+test_urcu_mb_reclaim: test_urcu_reclaim.c ${URCU_MB_RECLAIM}
+ $(CC) -DURCU_MB ${CFLAGS} $(LDFLAGS) -o $@ $(SRC_DEP)
+
test_qsbr: test_qsbr.c ${URCU_QSBR}
$(CC) ${CFLAGS} $(LDFLAGS) -o $@ $(SRC_DEP)
--- /dev/null
+/*
+ * test_urcu_reclaim.c
+ *
+ * Userspace RCU library - test program (with automatic reclamation)
+ *
+ * Copyright February 2009 - Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 _GNU_SOURCE
+#include <stdio.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <assert.h>
+#include <sys/syscall.h>
+#include <sched.h>
+
+#include "../arch.h"
+
+/* Make this big enough to include the POWER5+ L3 cacheline size of 256B */
+#define CACHE_LINE_SIZE 4096
+
+/* hardcoded number of CPUs */
+#define NR_CPUS 16384
+
+#if defined(_syscall0)
+_syscall0(pid_t, gettid)
+#elif defined(__NR_gettid)
+static inline pid_t gettid(void)
+{
+ return syscall(__NR_gettid);
+}
+#else
+#warning "use pid as tid"
+static inline pid_t gettid(void)
+{
+ return getpid();
+}
+#endif
+
+#ifndef DYNAMIC_LINK_TEST
+#define _LGPL_SOURCE
+#else
+#define debug_yield_read()
+#endif
+#include "../urcu.h"
+#include "../urcu-reclaim.h"
+
+struct test_array {
+ int a;
+};
+
+static volatile int test_go, test_stop;
+
+static unsigned long wdelay;
+
+static struct test_array *test_rcu_pointer;
+
+static unsigned long duration;
+
+/* read-side C.S. duration, in loops */
+static unsigned long rduration;
+
+static inline void loop_sleep(unsigned long l)
+{
+ while(l-- != 0)
+ cpu_relax();
+}
+
+static int verbose_mode;
+
+#define printf_verbose(fmt, args...) \
+ do { \
+ if (verbose_mode) \
+ printf(fmt, args); \
+ } while (0)
+
+static unsigned int cpu_affinities[NR_CPUS];
+static unsigned int next_aff = 0;
+static int use_affinity = 0;
+
+pthread_mutex_t affinity_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+static void set_affinity(void)
+{
+ cpu_set_t mask;
+ int cpu;
+ int ret;
+
+ if (!use_affinity)
+ return;
+
+ ret = pthread_mutex_lock(&affinity_mutex);
+ if (ret) {
+ perror("Error in pthread mutex lock");
+ exit(-1);
+ }
+ cpu = cpu_affinities[next_aff++];
+ ret = pthread_mutex_unlock(&affinity_mutex);
+ if (ret) {
+ perror("Error in pthread mutex unlock");
+ exit(-1);
+ }
+ CPU_ZERO(&mask);
+ CPU_SET(cpu, &mask);
+ sched_setaffinity(0, sizeof(mask), &mask);
+}
+
+/*
+ * returns 0 if test should end.
+ */
+static int test_duration_write(void)
+{
+ return !test_stop;
+}
+
+static int test_duration_read(void)
+{
+ return !test_stop;
+}
+
+static unsigned long long __thread nr_writes;
+static unsigned long long __thread nr_reads;
+
+static
+unsigned long long __attribute__((aligned(CACHE_LINE_SIZE))) *tot_nr_writes;
+
+static unsigned int nr_readers;
+static unsigned int nr_writers;
+
+pthread_mutex_t rcu_copy_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+void rcu_copy_mutex_lock(void)
+{
+ int ret;
+ ret = pthread_mutex_lock(&rcu_copy_mutex);
+ if (ret) {
+ perror("Error in pthread mutex lock");
+ exit(-1);
+ }
+}
+
+void rcu_copy_mutex_unlock(void)
+{
+ int ret;
+
+ ret = pthread_mutex_unlock(&rcu_copy_mutex);
+ if (ret) {
+ perror("Error in pthread mutex unlock");
+ exit(-1);
+ }
+}
+
+void *thr_reader(void *_count)
+{
+ unsigned long long *count = _count;
+ struct test_array *local_ptr;
+
+ printf_verbose("thread_begin %s, thread id : %lx, tid %lu\n",
+ "reader", pthread_self(), (unsigned long)gettid());
+
+ set_affinity();
+
+ rcu_register_thread();
+
+ while (!test_go)
+ {
+ }
+ smp_mb();
+
+ for (;;) {
+ rcu_read_lock();
+ local_ptr = rcu_dereference(test_rcu_pointer);
+ debug_yield_read();
+ if (local_ptr)
+ assert(local_ptr->a == 8);
+ if (unlikely(rduration))
+ loop_sleep(rduration);
+ rcu_read_unlock();
+ nr_reads++;
+ if (unlikely(!test_duration_read()))
+ break;
+ }
+
+ rcu_unregister_thread();
+
+ *count = nr_reads;
+ printf_verbose("thread_end %s, thread id : %lx, tid %lu\n",
+ "reader", pthread_self(), (unsigned long)gettid());
+ return ((void*)1);
+
+}
+
+void *thr_writer(void *data)
+{
+ unsigned long wtidx = (unsigned long)data;
+ struct test_array *new, *old = NULL;
+
+ printf_verbose("thread_begin %s, thread id : %lx, tid %lu\n",
+ "writer", pthread_self(), (unsigned long)gettid());
+
+ set_affinity();
+
+ rcu_reclaim_register_thread();
+
+ while (!test_go)
+ {
+ }
+ smp_mb();
+
+ for (;;) {
+ new = malloc(sizeof(*new));
+ new->a = 8;
+ old = rcu_xchg_pointer(&test_rcu_pointer, new);
+ rcu_reclaim_queue(old);
+ nr_writes++;
+ if (unlikely(!test_duration_write()))
+ break;
+ if (unlikely(wdelay))
+ loop_sleep(wdelay);
+ }
+
+ rcu_reclaim_unregister_thread();
+
+ printf_verbose("thread_end %s, thread id : %lx, tid %lu\n",
+ "writer", pthread_self(), (unsigned long)gettid());
+ tot_nr_writes[wtidx] = nr_writes;
+ return ((void*)2);
+}
+
+void show_usage(int argc, char **argv)
+{
+ printf("Usage : %s nr_readers nr_writers duration (s)", argv[0]);
+#ifdef DEBUG_YIELD
+ printf(" [-r] [-w] (yield reader and/or writer)");
+#endif
+ printf(" [-d delay] (writer period (us))");
+ printf(" [-c duration] (reader C.S. duration (in loops))");
+ printf(" [-v] (verbose output)");
+ printf(" [-a cpu#] [-a cpu#]... (affinity)");
+ printf("\n");
+}
+
+int main(int argc, char **argv)
+{
+ int err;
+ pthread_t *tid_reader, *tid_writer;
+ void *tret;
+ unsigned long long *count_reader;
+ unsigned long long tot_reads = 0, tot_writes = 0;
+ int i, a;
+
+ if (argc < 4) {
+ show_usage(argc, argv);
+ return -1;
+ }
+
+ err = sscanf(argv[1], "%u", &nr_readers);
+ if (err != 1) {
+ show_usage(argc, argv);
+ return -1;
+ }
+
+ err = sscanf(argv[2], "%u", &nr_writers);
+ if (err != 1) {
+ show_usage(argc, argv);
+ return -1;
+ }
+
+ err = sscanf(argv[3], "%lu", &duration);
+ if (err != 1) {
+ show_usage(argc, argv);
+ return -1;
+ }
+
+ for (i = 4; i < argc; i++) {
+ if (argv[i][0] != '-')
+ continue;
+ switch (argv[i][1]) {
+#ifdef DEBUG_YIELD
+ case 'r':
+ yield_active |= YIELD_READ;
+ break;
+ case 'w':
+ yield_active |= YIELD_WRITE;
+ break;
+#endif
+ case 'a':
+ if (argc < i + 2) {
+ show_usage(argc, argv);
+ return -1;
+ }
+ a = atoi(argv[++i]);
+ cpu_affinities[next_aff++] = a;
+ use_affinity = 1;
+ printf_verbose("Adding CPU %d affinity\n", a);
+ break;
+ case 'c':
+ if (argc < i + 2) {
+ show_usage(argc, argv);
+ return -1;
+ }
+ rduration = atol(argv[++i]);
+ break;
+ case 'd':
+ if (argc < i + 2) {
+ show_usage(argc, argv);
+ return -1;
+ }
+ wdelay = atol(argv[++i]);
+ break;
+ case 'v':
+ verbose_mode = 1;
+ break;
+ }
+ }
+
+ printf_verbose("running test for %lu seconds, %u readers, %u writers.\n",
+ duration, nr_readers, nr_writers);
+ printf_verbose("Writer delay : %lu loops.\n", wdelay);
+ printf_verbose("Reader duration : %lu loops.\n", rduration);
+ printf_verbose("thread %-6s, thread id : %lx, tid %lu\n",
+ "main", pthread_self(), (unsigned long)gettid());
+
+ tid_reader = malloc(sizeof(*tid_reader) * nr_readers);
+ tid_writer = malloc(sizeof(*tid_writer) * nr_writers);
+ count_reader = malloc(sizeof(*count_reader) * nr_readers);
+ tot_nr_writes = malloc(sizeof(*tot_nr_writes) * nr_writers);
+
+ next_aff = 0;
+
+ for (i = 0; i < nr_readers; i++) {
+ err = pthread_create(&tid_reader[i], NULL, thr_reader,
+ &count_reader[i]);
+ if (err != 0)
+ exit(1);
+ }
+ for (i = 0; i < nr_writers; i++) {
+ err = pthread_create(&tid_writer[i], NULL, thr_writer,
+ (void *)(long)i);
+ if (err != 0)
+ exit(1);
+ }
+
+ smp_mb();
+
+ test_go = 1;
+
+ sleep(duration);
+
+ test_stop = 1;
+
+ for (i = 0; i < nr_readers; i++) {
+ err = pthread_join(tid_reader[i], &tret);
+ if (err != 0)
+ exit(1);
+ tot_reads += count_reader[i];
+ }
+ for (i = 0; i < nr_writers; i++) {
+ err = pthread_join(tid_writer[i], &tret);
+ if (err != 0)
+ exit(1);
+ tot_writes += tot_nr_writes[i];
+ }
+
+ printf_verbose("total number of reads : %llu, writes %llu\n", tot_reads,
+ tot_writes);
+ printf("SUMMARY %-25s testdur %4lu nr_readers %3u rdur %6lu "
+ "nr_writers %3u "
+ "wdelay %6lu nr_reads %12llu nr_writes %12llu nr_ops %12llu\n",
+ argv[0], duration, nr_readers, rduration,
+ nr_writers, wdelay, tot_reads, tot_writes,
+ tot_reads + tot_writes);
+ free(tid_reader);
+ free(tid_writer);
+ free(count_reader);
+ free(tot_nr_writes);
+
+ return 0;
+}
--- /dev/null
+#ifndef _URCU_RECLAIM_STATIC_H
+#define _URCU_RECLAIM_STATIC_H
+
+/*
+ * urcu-static.h
+ *
+ * Userspace RCU header.
+ *
+ * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu.h for linking
+ * dynamically with the userspace rcu library.
+ *
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
+ *
+ * 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; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * 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
+ *
+ * IBM's contributions to this file may be relicensed under LGPLv2 or later.
+ */
+
+#include <stdlib.h>
+#include <pthread.h>
+
+#include <compiler.h>
+#include <arch.h>
+
+
+/*
+ * Number of entries in the per-thread reclaim queue. Must be power of 2.
+ */
+#define RECLAIM_QUEUE_SIZE (1 << 12)
+#define RECLAIM_QUEUE_MASK (RECLAIM_QUEUE_SIZE - 1)
+
+/*
+ * Identify a shared load. A smp_rmc() or smp_mc() should come before the load.
+ */
+#define _LOAD_SHARED(p) ACCESS_ONCE(p)
+
+/*
+ * Load a data from shared memory, doing a cache flush if required.
+ */
+#define LOAD_SHARED(p) \
+ ({ \
+ smp_rmc(); \
+ _LOAD_SHARED(p); \
+ })
+
+/*
+ * Identify a shared store. A smp_wmc() or smp_mc() should follow the store.
+ */
+#define _STORE_SHARED(x, v) ({ ACCESS_ONCE(x) = (v); })
+
+/*
+ * Store v into x, where x is located in shared memory. Performs the required
+ * cache flush after writing. Returns v.
+ */
+#define STORE_SHARED(x, v) \
+ ({ \
+ _STORE_SHARED(x, v); \
+ smp_wmc(); \
+ (v); \
+ })
+
+/*
+ * This code section can only be included in LGPL 2.1 compatible source code.
+ * See below for the function call wrappers which can be used in code meant to
+ * be only linked with the Userspace RCU library. This comes with a small
+ * performance degradation on the read-side due to the added function calls.
+ * This is required to permit relinking with newer versions of the library.
+ */
+
+#ifdef DEBUG_RCU
+#define rcu_assert(args...) assert(args)
+#else
+#define rcu_assert(args...)
+#endif
+
+struct reclaim_queue {
+ unsigned long head; /* add element at head */
+ unsigned long tail; /* next element to remove at tail */
+ void **q;
+};
+
+extern struct reclaim_queue __thread reclaim_queue;
+
+extern void rcu_reclaim_barrier_thread(void);
+
+/*
+ * not signal-safe.
+ */
+static inline void _rcu_reclaim_queue(void *p)
+{
+ unsigned long head, tail;
+
+ /*
+ * Head is only modified by ourself. Tail can be modified by reclamation
+ * thread.
+ */
+ head = reclaim_queue.head;
+ tail = LOAD_SHARED(reclaim_queue.tail);
+
+ /*
+ * If queue is full, empty it ourself.
+ */
+ if (unlikely(head - tail >= RECLAIM_QUEUE_SIZE)) {
+ assert(head - tail == RECLAIM_QUEUE_SIZE);
+ rcu_reclaim_barrier_thread();
+ assert(head - LOAD_SHARED(reclaim_queue.tail) == 0);
+ }
+
+ smp_wmb(); /* Publish new pointer before write q[] */
+ _STORE_SHARED(reclaim_queue.q[head & RECLAIM_QUEUE_MASK], p);
+ smp_wmb(); /* Write q[] before head. */
+ STORE_SHARED(reclaim_queue.head, head + 1);
+}
+
+#endif /* _URCU_RECLAIM_STATIC_H */
--- /dev/null
+/*
+ * urcu-reclaim.c
+ *
+ * Userspace RCU library - batch memory reclamation
+ *
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ *
+ * 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; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * 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
+ */
+
+#include <stdio.h>
+#include <pthread.h>
+#include <signal.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <poll.h>
+
+#include "urcu-reclaim-static.h"
+/* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
+#include "urcu-reclaim.h"
+
+void __attribute__((constructor)) urcu_reclaim_init(void);
+void __attribute__((destructor)) urcu_reclaim_exit(void);
+
+extern void synchronize_rcu(void);
+
+static int init_done;
+
+/*
+ * urcu_reclaim_mutex nests inside reclaim_thread_mutex.
+ */
+static pthread_mutex_t urcu_reclaim_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t reclaim_thread_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/*
+ * Written to only by each individual reader. Read by both the reader and the
+ * writers.
+ */
+struct reclaim_queue __thread reclaim_queue;
+
+/* Thread IDs of registered readers */
+#define INIT_NUM_THREADS 4
+
+struct reader_registry {
+ pthread_t tid;
+ struct reclaim_queue *reclaim_queue;
+ unsigned long last_head;
+};
+
+static struct reader_registry *registry;
+static int num_readers, alloc_readers;
+
+static pthread_t tid_reclaim;
+static int exit_reclaim;
+
+static void internal_urcu_lock(pthread_mutex_t *mutex)
+{
+ int ret;
+
+#ifndef DISTRUST_SIGNALS_EXTREME
+ ret = pthread_mutex_lock(mutex);
+ if (ret) {
+ perror("Error in pthread mutex lock");
+ exit(-1);
+ }
+#else /* #ifndef DISTRUST_SIGNALS_EXTREME */
+ while ((ret = pthread_mutex_trylock(mutex)) != 0) {
+ if (ret != EBUSY && ret != EINTR) {
+ printf("ret = %d, errno = %d\n", ret, errno);
+ perror("Error in pthread mutex lock");
+ exit(-1);
+ }
+ poll(NULL,0,10);
+ }
+#endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */
+}
+
+static void internal_urcu_unlock(pthread_mutex_t *mutex)
+{
+ int ret;
+
+ ret = pthread_mutex_unlock(mutex);
+ if (ret) {
+ perror("Error in pthread mutex unlock");
+ exit(-1);
+ }
+}
+
+/*
+ * Must be called after Q.S. is reached.
+ */
+static void rcu_reclaim_barrier_queue(struct reclaim_queue *queue,
+ unsigned long head)
+{
+ unsigned long i;
+
+ /*
+ * Tail is only modified when lock is held.
+ * Head is only modified by owner thread.
+ */
+
+ for (i = queue->tail; i != head; i++) {
+ smp_rmb(); /* read head before q[]. */
+ free(LOAD_SHARED(queue->q[i & RECLAIM_QUEUE_MASK]));
+ }
+ smp_mb(); /* push tail after having used q[] */
+ STORE_SHARED(queue->tail, i);
+}
+
+static void _rcu_reclaim_barrier_thread(void)
+{
+ unsigned long head;
+
+ head = reclaim_queue.head;
+ synchronize_rcu();
+ rcu_reclaim_barrier_queue(&reclaim_queue, head);
+}
+
+
+void rcu_reclaim_barrier_thread(void)
+{
+ internal_urcu_lock(&urcu_reclaim_mutex);
+ _rcu_reclaim_barrier_thread();
+ internal_urcu_unlock(&urcu_reclaim_mutex);
+}
+
+void rcu_reclaim_barrier(void)
+{
+ struct reader_registry *index;
+
+ if (!registry)
+ return;
+
+ internal_urcu_lock(&urcu_reclaim_mutex);
+ for (index = registry; index < registry + num_readers; index++)
+ index->last_head = LOAD_SHARED(index->reclaim_queue->head);
+ synchronize_rcu();
+ for (index = registry; index < registry + num_readers; index++)
+ rcu_reclaim_barrier_queue(index->reclaim_queue,
+ index->last_head);
+ internal_urcu_unlock(&urcu_reclaim_mutex);
+}
+
+void *thr_reclaim(void *args)
+{
+ for (;;) {
+ if (LOAD_SHARED(exit_reclaim))
+ break;
+ poll(NULL,0,100); /* wait for 100ms */
+ rcu_reclaim_barrier();
+ }
+
+ return NULL;
+}
+
+/*
+ * library wrappers to be used by non-LGPL compatible source code.
+ */
+
+void rcu_reclaim_queue(void *p)
+{
+ _rcu_reclaim_queue(p);
+}
+
+static void rcu_add_reader(pthread_t id)
+{
+ struct reader_registry *oldarray;
+
+ if (!registry) {
+ alloc_readers = INIT_NUM_THREADS;
+ num_readers = 0;
+ registry =
+ malloc(sizeof(struct reader_registry) * alloc_readers);
+ }
+ if (alloc_readers < num_readers + 1) {
+ oldarray = registry;
+ registry = malloc(sizeof(struct reader_registry)
+ * (alloc_readers << 1));
+ memcpy(registry, oldarray,
+ sizeof(struct reader_registry) * alloc_readers);
+ alloc_readers <<= 1;
+ free(oldarray);
+ }
+ registry[num_readers].tid = id;
+ /* reference to the TLS of _this_ reader thread. */
+ registry[num_readers].reclaim_queue = &reclaim_queue;
+ num_readers++;
+}
+
+/*
+ * Never shrink (implementation limitation).
+ * This is O(nb threads). Eventually use a hash table.
+ */
+static void rcu_remove_reader(pthread_t id)
+{
+ struct reader_registry *index;
+
+ assert(registry != NULL);
+ for (index = registry; index < registry + num_readers; index++) {
+ if (pthread_equal(index->tid, id)) {
+ memcpy(index, ®istry[num_readers - 1],
+ sizeof(struct reader_registry));
+ registry[num_readers - 1].tid = 0;
+ registry[num_readers - 1].reclaim_queue = NULL;
+ num_readers--;
+ return;
+ }
+ }
+ /* Hrm not found, forgot to register ? */
+ assert(0);
+}
+
+static void start_reclaim_thread(void)
+{
+ int ret;
+
+ ret = pthread_create(&tid_reclaim, NULL, thr_reclaim,
+ NULL);
+ assert(!ret);
+}
+
+static void stop_reclaim_thread(void)
+{
+ int ret;
+ void *tret;
+
+ STORE_SHARED(exit_reclaim, 1);
+ ret = pthread_join(tid_reclaim, &tret);
+ assert(!ret);
+}
+
+void rcu_reclaim_register_thread(void)
+{
+ int readers;
+
+ internal_urcu_lock(&reclaim_thread_mutex);
+ internal_urcu_lock(&urcu_reclaim_mutex);
+ /* In case gcc does not support constructor attribute */
+ urcu_reclaim_init();
+ reclaim_queue.q = malloc(sizeof(void *) * RECLAIM_QUEUE_SIZE);
+ rcu_add_reader(pthread_self());
+ readers = num_readers;
+ internal_urcu_unlock(&urcu_reclaim_mutex);
+
+ if (readers == 1)
+ start_reclaim_thread();
+ internal_urcu_unlock(&reclaim_thread_mutex);
+}
+
+void rcu_reclaim_unregister_thread(void)
+{
+ int readers;
+
+ internal_urcu_lock(&reclaim_thread_mutex);
+ internal_urcu_lock(&urcu_reclaim_mutex);
+ rcu_remove_reader(pthread_self());
+ _rcu_reclaim_barrier_thread();
+ free(reclaim_queue.q);
+ reclaim_queue.q = NULL;
+ readers = num_readers;
+ internal_urcu_unlock(&urcu_reclaim_mutex);
+
+ if (readers == 0)
+ stop_reclaim_thread();
+ internal_urcu_unlock(&reclaim_thread_mutex);
+}
+
+/*
+ * urcu_init constructor. Called when the library is linked, but also when
+ * reader threads are calling rcu_register_thread(). Should only be called by a
+ * single thread at a given time. This is ensured by holing the
+ * internal_urcu_lock(&urcu_reclaim_mutex) from rcu_register_thread() or by
+ * running at library load time, which should not be executed by multiple
+ * threads nor concurrently with rcu_register_thread() anyway.
+ */
+void urcu_reclaim_init(void)
+{
+ if (init_done)
+ return;
+ init_done = 1;
+}
+
+void urcu_reclaim_exit(void)
+{
+ free(registry);
+}
--- /dev/null
+#ifndef _URCU_RECLAIM_H
+#define _URCU_RECLAIM_H
+
+/*
+ * urcu-reclaim.h
+ *
+ * Userspace RCU header - memory reclamation
+ *
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
+ *
+ * LGPL-compatible code should include this header with :
+ *
+ * #define _LGPL_SOURCE
+ * #include <urcu-reclaim.h>
+ *
+ * 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; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * 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
+ */
+
+#include <stdlib.h>
+#include <pthread.h>
+
+/*
+ * Important !
+ *
+ * Each thread queuing memory reclamation must be registered with
+ * rcu_reclaim_register_thread(). rcu_reclaim_unregister_thread() should be
+ * called before the thread exits.
+ */
+
+#ifdef _LGPL_SOURCE
+
+#include <urcu-reclaim-static.h>
+
+/*
+ * Mappings for static use of the userspace RCU library.
+ * Should only be used in LGPL-compatible code.
+ */
+
+#define rcu_reclaim_queue _rcu_reclaim_queue
+
+#else /* !_LGPL_SOURCE */
+
+/*
+ * library wrappers to be used by non-LGPL compatible source code.
+ */
+
+extern void rcu_reclaim_queue(void *p);
+
+#endif /* !_LGPL_SOURCE */
+
+/*
+ * Thread registration for reclamation.
+ */
+extern void rcu_reclaim_register_thread(void);
+extern void rcu_reclaim_unregister_thread(void);
+extern void rcu_reclaim_barrier(void);
+extern void rcu_reclaim_barrier_thread(void);
+
+#endif /* _URCU_RECLAIM_H */
projects / urcu.git / commitdiff
