Cap the size of the poll kick freelist.

This caps the size of the poll kick freelist at the arbitrary value of
25.

2 files changed, 49 insertions, 11 deletions

diff --git a/src/core/iomgr/pollset_kick_posix.c b/src/core/iomgr/pollset_kick_posix.c
index d16e49e459..9f85b6137a 100644
--- a/src/core/iomgr/pollset_kick_posix.c
+++ b/src/core/iomgr/pollset_kick_posix.c
@@ -43,6 +43,9 @@
 
 /* This implementation is based on a freelist of pipes. */
 
+#define GRPC_MAX_CACHED_PIPES 50
+#define GRPC_PIPE_LOW_WATERMARK 25
+
 typedef struct grpc_kick_pipe_info {
   int pipe_read_fd;
   int pipe_write_fd;
@@ -50,14 +53,16 @@ typedef struct grpc_kick_pipe_info {
 } grpc_kick_pipe_info;
 
 static grpc_kick_pipe_info *pipe_freelist = NULL;
+static int pipe_freelist_count = 0;
 static gpr_mu pipe_freelist_mu;
 
-static grpc_kick_pipe_info *allocate_pipe() {
+static grpc_kick_pipe_info *allocate_pipe(void) {
   grpc_kick_pipe_info *info;
   gpr_mu_lock(&pipe_freelist_mu);
   if (pipe_freelist != NULL) {
     info = pipe_freelist;
     pipe_freelist = pipe_freelist->next;
+    --pipe_freelist_count;
   } else {
     int pipefd[2];
     /* TODO(klempner): Make this nonfatal */
@@ -73,11 +78,26 @@ static grpc_kick_pipe_info *allocate_pipe() {
   return info;
 }
 
+static void destroy_pipe(void) {
+  /* assumes pipe_freelist_mu is held */
+  grpc_kick_pipe_info *current = pipe_freelist;
+  pipe_freelist = pipe_freelist->next;
+  pipe_freelist_count--;
+  close(current->pipe_read_fd);
+  close(current->pipe_write_fd);
+  gpr_free(current);
+}
+
 static void free_pipe(grpc_kick_pipe_info *pipe_info) {
-  /* TODO(klempner): Start closing pipes if the free list gets too large */
   gpr_mu_lock(&pipe_freelist_mu);
   pipe_info->next = pipe_freelist;
   pipe_freelist = pipe_info;
+  pipe_freelist_count++;
+  if (pipe_freelist_count > GRPC_MAX_CACHED_PIPES) {
+    while (pipe_freelist_count > GRPC_PIPE_LOW_WATERMARK) {
+      destroy_pipe();
+    }
+  }
   gpr_mu_unlock(&pipe_freelist_mu);
 }
 
@@ -88,11 +108,7 @@ void grpc_pollset_kick_global_init() {
 
 void grpc_pollset_kick_global_destroy() {
   while (pipe_freelist != NULL) {
-    grpc_kick_pipe_info *current = pipe_freelist;
-    pipe_freelist = pipe_freelist->next;
-    close(current->pipe_read_fd);
-    close(current->pipe_write_fd);
-    gpr_free(current);
+    destroy_pipe();
   }
   gpr_mu_destroy(&pipe_freelist_mu);
 }
diff --git a/test/core/iomgr/poll_kick_test.c b/test/core/iomgr/poll_kick_test.c
index 9f0d0f38b3..c30a7b9ee0 100644
--- a/test/core/iomgr/poll_kick_test.c
+++ b/test/core/iomgr/poll_kick_test.c
@@ -33,16 +33,17 @@
 
 #include "src/core/iomgr/pollset_kick.h"
 
+#include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include "test/core/util/test_config.h"
 
-static void test_allocation() {
+static void test_allocation(void) {
   grpc_pollset_kick_state state;
   grpc_pollset_kick_init(&state);
   grpc_pollset_kick_destroy(&state);
 }
 
-static void test_non_kick() {
+static void test_non_kick(void) {
   grpc_pollset_kick_state state;
   int fd;
 
@@ -54,7 +55,7 @@ static void test_non_kick() {
   grpc_pollset_kick_destroy(&state);
 }
 
-static void test_basic_kick() {
+static void test_basic_kick(void) {
   /* Kicked during poll */
   grpc_pollset_kick_state state;
   int fd;
@@ -73,7 +74,7 @@ static void test_basic_kick() {
   grpc_pollset_kick_destroy(&state);
 }
 
-static void test_non_poll_kick() {
+static void test_non_poll_kick(void) {
   /* Kick before entering poll */
   grpc_pollset_kick_state state;
   int fd;
@@ -86,6 +87,26 @@ static void test_non_poll_kick() {
   grpc_pollset_kick_destroy(&state);
 }
 
+#define GRPC_MAX_CACHED_PIPES 50
+
+static void test_over_free(void) {
+  /* Check high watermark pipe free logic */
+  int i;
+  struct grpc_pollset_kick_state *kick_state =
+      gpr_malloc(sizeof(grpc_pollset_kick_state) * GRPC_MAX_CACHED_PIPES);
+  for (i = 0; i < GRPC_MAX_CACHED_PIPES; ++i) {
+    int fd;
+    grpc_pollset_kick_init(&kick_state[i]);
+    fd = grpc_pollset_kick_pre_poll(&kick_state[i]);
+    GPR_ASSERT(fd >= 0);
+  }
+
+  for (i = 0; i < GRPC_MAX_CACHED_PIPES; ++i) {
+    grpc_pollset_kick_post_poll(&kick_state[i]);
+    grpc_pollset_kick_destroy(&kick_state[i]);
+  }
+}
+
 int main(int argc, char **argv) {
   grpc_test_init(argc, argv);
 
@@ -95,6 +116,7 @@ int main(int argc, char **argv) {
   test_basic_kick();
   test_non_poll_kick();
   test_non_kick();
+  test_over_free();
 
   grpc_pollset_kick_global_destroy();
   return 0;