Move destroy cells into a separate queue type of their own, to save RAM

We've been seeing problems with destroy cells queues taking up a
huge amount of RAM.  We can mitigate this, since while a full packed
destroy cell takes 514 bytes, we only need 5 bytes to remember a
circuit ID and a reason.

Fixes bug 24666. Bugfix on 0.2.5.1-alpha, when destroy cell queues
were introduced.

1 files changed, 15 insertions, 0 deletions

diff --git a/src/or/or.h b/src/or/or.h
index adf3cfa866..b6a3f62efe 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -1121,6 +1121,21 @@ typedef struct cell_queue_t {
   int n; /**< The number of cells in the queue. */
 } cell_queue_t;
 
+/** A single queued destroy cell. */
+typedef struct destroy_cell_t {
+  TOR_SIMPLEQ_ENTRY(destroy_cell_t) next;
+  circid_t circid;
+  uint32_t inserted_time; /** Timestamp when this was queued. */
+  uint8_t reason;
+} destroy_cell_t;
+
+/** A queue of destroy cells on a channel. */
+typedef struct destroy_cell_queue_t {
+  /** Linked list of packed_cell_t */
+  TOR_SIMPLEQ_HEAD(dcell_simpleq, destroy_cell_t) head;
+  int n; /**< The number of cells in the queue. */
+} destroy_cell_queue_t;
+
 /** Beginning of a RELAY cell payload. */
 typedef struct {
   uint8_t command; /**< The end-to-end relay command. */