src/utils_random.[ch]: Provide thread-safe random numbers.

diff --git a/src/Makefile.am b/src/Makefile.am
index 617d3ec758ac8861671d989ba591dd3c8b22868a..34012a7f1bb1463caead9675a9f15eda678a6d47 100644 (file)
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -33,6 +33,7 @@ collectd_SOURCES = collectd.c collectd.h \
                   utils_ignorelist.c utils_ignorelist.h \
                   utils_llist.c utils_llist.h \
                   utils_parse_option.c utils_parse_option.h \
+                  utils_random.c utils_random.h \
                   utils_tail_match.c utils_tail_match.h \
                   utils_match.c utils_match.h \
                   utils_subst.c utils_subst.h \

diff --git a/src/utils_random.c b/src/utils_random.c
new file mode 100644 (file)
index 0000000..b873845
--- /dev/null
+++ b/src/utils_random.c
@@ -0,0 +1,75 @@
+/**
+ * collectd - src/utils_random.c
+ * Copyright (C) 2013       Florian Forster
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Authors:
+ *   Florian Forster <octo at collectd.org>
+ **/
+
+#include "collectd.h"
+#include "utils_time.h"
+
+#include <pthread.h>
+
+static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
+static _Bool have_seed = 0;
+static unsigned short seed[3];
+
+static void cdrand_seed (void)
+{
+  cdtime_t t;
+
+  if (have_seed)
+    return;
+
+  t = cdtime();
+
+  seed[0] = (unsigned short) t;
+  seed[1] = (unsigned short) (t >> 16);
+  seed[2] = (unsigned short) (t >> 32);
+
+  have_seed = 1;
+}
+
+double cdrand_d (void)
+{
+  double r;
+
+  pthread_mutex_lock (&lock);
+  cdrand_seed ();
+  r = erand48 (seed);
+  pthread_mutex_unlock (&lock);
+
+  return (r);
+}
+
+long cdrand_range (long min, long max)
+{
+  long range;
+  long r;
+
+  range = 1 + max - min;
+
+  r = (long) (0.5 + (cdrand_d () * range));
+  r += min;
+
+  return (r);
+}

diff --git a/src/utils_random.h b/src/utils_random.h
new file mode 100644 (file)
index 0000000..b05f4c8
--- /dev/null
+++ b/src/utils_random.h
@@ -0,0 +1,40 @@
+/**
+ * collectd - src/utils_random.h
+ * Copyright (C) 2013       Florian Forster
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Authors:
+ *   Florian Forster <octo at collectd.org>
+ **/
+
+/**
+ * Returns a random double value in the range [0..1), i.e. excluding 1.
+ *
+ * This function is thread- and reentrant-safe.
+ */
+double cdrand_d (void);
+
+/**
+ * Returns a random long between min and max, inclusively.
+ *
+ * If min is larger than max, the result may be rounded incorrectly and may be
+ * outside the intended range. This function is thread- and reentrant-safe.
+ */
+long cdrand_range (long min, long max);