common: compile libcommon as C++

[lttng-tools.git] / src / common / defaults.cpp

diff --git a/src/common/defaults.cpp b/src/common/defaults.cpp
new file mode 100644 (file)
index 0000000..5ecb435
--- /dev/null
+++ b/src/common/defaults.cpp
@@ -0,0 +1,154 @@
+/*
+ * Copyright (C) 2012 Simon Marchi <simon.marchi@polymtl.ca>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#define _LGPL_SOURCE
+#include <stddef.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <sys/resource.h>
+#include <pthread.h>
+#include <algorithm>
+
+#include "defaults.h"
+#include "macros.h"
+#include "error.h"
+
+static int pthread_attr_init_done;
+static pthread_attr_t tattr;
+
+static size_t get_page_size(void)
+{
+       const long ret = sysconf(_SC_PAGE_SIZE);
+
+       if (ret < 0) {
+               /*
+                * Fatal error since there is no safe way to recover from this.
+                */
+               PERROR("Failed to get system page size using sysconf(_SC_PAGE_SIZE)");
+               abort();
+       }
+
+       return (size_t) ret;
+}
+
+size_t default_get_channel_subbuf_size(void)
+{
+       return std::max<size_t>(_DEFAULT_CHANNEL_SUBBUF_SIZE, get_page_size());
+}
+
+size_t default_get_metadata_subbuf_size(void)
+{
+       return std::max<size_t>(DEFAULT_METADATA_SUBBUF_SIZE, get_page_size());
+}
+
+size_t default_get_kernel_channel_subbuf_size(void)
+{
+       return std::max<size_t>(DEFAULT_KERNEL_CHANNEL_SUBBUF_SIZE, get_page_size());
+}
+
+size_t default_get_ust_pid_channel_subbuf_size(void)
+{
+       return std::max<size_t>(DEFAULT_UST_PID_CHANNEL_SUBBUF_SIZE, get_page_size());
+}
+
+size_t default_get_ust_uid_channel_subbuf_size(void)
+{
+       return std::max<size_t>(DEFAULT_UST_UID_CHANNEL_SUBBUF_SIZE, get_page_size());
+}
+
+pthread_attr_t *default_pthread_attr(void)
+{
+       if (pthread_attr_init_done) {
+               return &tattr;
+       }
+
+       WARN("Uninitialized pthread attributes, using libc defaults.");
+       return NULL;
+}
+
+static void __attribute__((constructor)) init_default_pthread_attr(void)
+{
+       int ret;
+       struct rlimit rlim;
+       size_t pthread_ss, system_ss, selected_ss;
+
+       ret = pthread_attr_init(&tattr);
+       if (ret) {
+               errno = ret;
+               PERROR("pthread_attr_init");
+               goto error;
+       }
+
+       /* Get system stack size limits. */
+       ret = getrlimit(RLIMIT_STACK, &rlim);
+       if (ret < 0) {
+               PERROR("getrlimit");
+               goto error_destroy;
+       }
+       DBG("Stack size limits: soft %lld, hard %lld bytes",
+                       (long long) rlim.rlim_cur,
+                       (long long) rlim.rlim_max);
+
+       /*
+        * getrlimit() may return a stack size of "-1", meaning "unlimited".
+        * In this case, we impose a known-good default minimum value which will
+        * override the libc's default stack size if it is smaller.
+        */
+       system_ss = rlim.rlim_cur != -1 ? rlim.rlim_cur :
+                       DEFAULT_LTTNG_THREAD_STACK_SIZE;
+
+       /* Get pthread default thread stack size. */
+       ret = pthread_attr_getstacksize(&tattr, &pthread_ss);
+       if (ret < 0) {
+               PERROR("pthread_attr_getstacksize");
+               goto error_destroy;
+       }
+       DBG("Default pthread stack size is %zu bytes", pthread_ss);
+
+       selected_ss = std::max(pthread_ss, system_ss);
+       if (selected_ss < DEFAULT_LTTNG_THREAD_STACK_SIZE) {
+               DBG("Default stack size is too small, setting it to %zu bytes",
+                       (size_t) DEFAULT_LTTNG_THREAD_STACK_SIZE);
+               selected_ss = DEFAULT_LTTNG_THREAD_STACK_SIZE;
+       }
+
+       if (rlim.rlim_max > 0 && selected_ss > rlim.rlim_max) {
+               WARN("Your system's stack size restrictions (%zu bytes) may be too low for the LTTng daemons to function properly, please set the stack size limit to at least %zu bytes to ensure reliable operation",
+                       (size_t) rlim.rlim_max, (size_t) DEFAULT_LTTNG_THREAD_STACK_SIZE);
+               selected_ss = (size_t) rlim.rlim_max;
+       }
+
+       ret = pthread_attr_setstacksize(&tattr, selected_ss);
+       if (ret < 0) {
+               PERROR("pthread_attr_setstacksize");
+               goto error_destroy;
+       }
+       pthread_attr_init_done = 1;
+error:
+       return;
+error_destroy:
+       ret = pthread_attr_destroy(&tattr);
+       if (ret) {
+               errno = ret;
+               PERROR("pthread_attr_destroy");
+       }
+}
+
+static void __attribute__((destructor)) fini_default_pthread_attr(void)
+{
+       int ret;
+
+       if (!pthread_attr_init_done) {
+               return;
+       }
+
+       ret = pthread_attr_destroy(&tattr);
+       if (ret) {
+               errno = ret;
+               PERROR("pthread_attr_destroy");
+       }
+}