Throttling implementation

Based on sliding window algorithm

CMakeLists.txt

@@ -112,6 +112,7 @@ option(FLB_FILTER_GREP     "Enable grep filter"                 Yes)
 option(FLB_FILTER_STDOUT   "Enable stdout filter"               Yes)
 option(FLB_FILTER_PARSER   "Enable parser filter"               Yes)
 option(FLB_FILTER_KUBERNETES "Enable kubernetes filter"         Yes)
+option(FLB_FILTER_THROTTLE "Enable throttle filter"             Yes)
 option(FLB_FILTER_RECORD_MODIFIER "Enable record_modifier filter" Yes)
 
 # Enable all features

plugins/CMakeLists.txt

@@ -142,6 +142,7 @@ if (NOT CMAKE_SYSTEM_NAME MATCHES "Windows")
   REGISTER_FILTER_PLUGIN("filter_grep")
 endif()
 REGISTER_FILTER_PLUGIN("filter_stdout")
+REGISTER_FILTER_PLUGIN("filter_throttle")
 
 if(FLB_REGEX)
   REGISTER_FILTER_PLUGIN("filter_kubernetes")

plugins/filter_throttle/CMakeLists.txt

@@ -0,0 +1,8 @@
+set(src
+  window.c
+  throttle.c
+  c-strtod.c
+  xstrtod.c
+  )
+
+FLB_PLUGIN(filter_throttle "${src}" "")

plugins/filter_throttle/c-strtod.c

@@ -0,0 +1,110 @@
+/* Convert string to double, using the C locale.
+
+   Copyright (C) 2003-2004, 2006, 2009-2016 Free Software Foundation, Inc.
+
+   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 3 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, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by Paul Eggert.  */
+
+#include "c-strtod.h"
+
+#include <errno.h>
+#include <locale.h>
+#include <stdlib.h>
+#include <string.h>
+
+#if LONG
+# define C_STRTOD c_strtold
+# define DOUBLE long double
+# define STRTOD_L strtold_l
+#else
+# define C_STRTOD c_strtod
+# define DOUBLE double
+# define STRTOD_L strtod_l
+#endif
+
+/* c_strtold falls back on strtod if strtold doesn't conform to C99.  */
+#if LONG && HAVE_C99_STRTOLD
+# define STRTOD strtold
+#else
+# define STRTOD strtod
+#endif
+
+#if defined LC_ALL_MASK && (LONG ? HAVE_STRTOLD_L : HAVE_STRTOD_L)
+
+/* Cache for the C locale object.
+   Marked volatile so that different threads see the same value
+   (avoids locking).  */
+static volatile locale_t c_locale_cache;
+
+/* Return the C locale object, or (locale_t) 0 with errno set
+   if it cannot be created.  */
+static locale_t
+c_locale (void)
+{
+  if (!c_locale_cache)
+    c_locale_cache = newlocale (LC_ALL_MASK, "C", (locale_t) 0);
+  return c_locale_cache;
+}
+
+#endif
+
+DOUBLE
+C_STRTOD (char const *nptr, char **endptr)
+{
+  DOUBLE r;
+
+#if defined LC_ALL_MASK && (LONG ? HAVE_STRTOLD_L : HAVE_STRTOD_L)
+
+  locale_t locale = c_locale ();
+  if (!locale)
+    {
+      if (endptr)
+        *endptr = (char *) nptr;
+      return 0; /* errno is set here */
+    }
+
+  r = STRTOD_L (nptr, endptr, locale);
+
+#else
+
+  char *saved_locale = setlocale (LC_NUMERIC, NULL);
+
+  if (saved_locale)
+    {
+      saved_locale = strdup (saved_locale);
+      if (saved_locale == NULL)
+        {
+          if (endptr)
+            *endptr = (char *) nptr;
+          return 0; /* errno is set here */
+        }
+      setlocale (LC_NUMERIC, "C");
+    }
+
+  r = STRTOD (nptr, endptr);
+
+  if (saved_locale)
+    {
+      int saved_errno = errno;
+
+      setlocale (LC_NUMERIC, saved_locale);
+      free (saved_locale);
+      errno = saved_errno;
+    }
+
+#endif
+
+  return r;
+}

plugins/filter_throttle/c-strtod.h

@@ -0,0 +1,37 @@
+/* Convert string to double, using the C locale.  -*- coding: utf-8 -*-
+
+   Copyright (C) 2003-2004, 2009-2016 Free Software Foundation, Inc.
+
+   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 3 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, see <http://www.gnu.org/licenses/>.  */
+
+/* Parse the initial portion of the string pointed to by NPTR as a floating-
+   point number (in decimal or hexadecimal notation), like in the C locale:
+   accepting only the ASCII digits '0'..'9', and only '.' as decimal point
+   character.
+   If ENDPTR is not NULL, set *ENDPTR to point to the first byte beyond the
+   parsed number or to NPTR if the string does not start with a parsable
+   number.
+   Return value:
+   - If successful, return the value as a double or 'long double',
+     respectively, and don't modify errno.
+   - In case of overflow, return ±HUGE_VAL or ±HUGE_VALL, respectively, and
+     set errno to ERANGE.
+   - In case of underflow, return a value very near to 0 and set errno to
+     ERANGE.
+   - If the string does not start with a number at all, return 0 (and recall
+     that if ENDPTR != NULL, *ENDPTR is set to NPTR), and maybe set errno to
+     EINVAL.
+   - In case of other error, return 0 and set errno, for example to ENOMEM.  */
+extern double      c_strtod  (char const *nptr, char **endptr);
+extern long double c_strtold (char const *nptr, char **endptr);