1 files changed, 29 insertions, 1 deletions
diff --git a/src/core/lib/support/mpscq.h b/src/core/lib/support/mpscq.h
index 1cc9d89feb..fb22742050 100644
--- a/src/core/lib/support/mpscq.h
+++ b/src/core/lib/support/mpscq.h
@@ -20,6 +20,7 @@
 #define GRPC_CORE_LIB_SUPPORT_MPSCQ_H
 
 #include <grpc/support/atm.h>
+#include <grpc/support/sync.h>
 #include <stdbool.h>
 #include <stddef.h>
 
@@ -49,13 +50,40 @@ typedef struct gpr_mpscq {
 void gpr_mpscq_init(gpr_mpscq* q);
 void gpr_mpscq_destroy(gpr_mpscq* q);
 // Push a node
-void gpr_mpscq_push(gpr_mpscq* q, gpr_mpscq_node* n);
+// Thread safe - can be called from multiple threads concurrently
+// Returns true if this was possibly the first node (may return true
+// sporadically, will not return false sporadically)
+bool gpr_mpscq_push(gpr_mpscq* q, gpr_mpscq_node* n);
 // Pop a node (returns NULL if no node is ready - which doesn't indicate that
 // the queue is empty!!)
+// Thread compatible - can only be called from one thread at a time
 gpr_mpscq_node* gpr_mpscq_pop(gpr_mpscq* q);
 // Pop a node; sets *empty to true if the queue is empty, or false if it is not
 gpr_mpscq_node* gpr_mpscq_pop_and_check_end(gpr_mpscq* q, bool* empty);
 
+// An mpscq with a lock: it's safe to pop from multiple threads, but doing
+// only one thread will succeed concurrently
+typedef struct gpr_locked_mpscq {
+  gpr_mpscq queue;
+  gpr_mu mu;
+} gpr_locked_mpscq;
+
+void gpr_locked_mpscq_init(gpr_locked_mpscq* q);
+void gpr_locked_mpscq_destroy(gpr_locked_mpscq* q);
+// Push a node
+// Thread safe - can be called from multiple threads concurrently
+// Returns true if this was possibly the first node (may return true
+// sporadically, will not return false sporadically)
+bool gpr_locked_mpscq_push(gpr_locked_mpscq* q, gpr_mpscq_node* n);
+
+// Pop a node (returns NULL if no node is ready - which doesn't indicate that
+// the queue is empty!!)
+// Thread safe - can be called from multiple threads concurrently
+gpr_mpscq_node* gpr_locked_mpscq_try_pop(gpr_locked_mpscq* q);
+
+// Pop a node.  Returns NULL only if the queue was empty at some point after
+// calling this function
+gpr_mpscq_node* gpr_locked_mpscq_pop(gpr_locked_mpscq* q);
 #ifdef __cplusplus
 }
 #endif