Have the OOM handler also count the age the data in a stream buffer

src/or/buffers.c

@@ -68,6 +68,8 @@ typedef struct chunk_t {
   size_t datalen; /**< The number of bytes stored in this chunk */
   size_t memlen; /**< The number of usable bytes of storage in <b>mem</b>. */
   char *data; /**< A pointer to the first byte of data stored in <b>mem</b>. */
+  uint32_t inserted_time; /**< Timestamp in truncated ms since epoch
+                           * when this chunk was inserted. */
   char mem[FLEXIBLE_ARRAY_MEMBER]; /**< The actual memory used for storage in
                 * this chunk. */
 } chunk_t;
@@ -139,6 +141,9 @@ static chunk_freelist_t freelists[] = {
  * could help with? */
 static uint64_t n_freelist_miss = 0;
 
+/** DOCDOC */
+static size_t total_bytes_allocated_in_chunks = 0;
+
 static void assert_freelist_ok(chunk_freelist_t *fl);
 
 /** Return the freelist to hold chunks of size <b>alloc</b>, or NULL if
@@ -172,6 +177,8 @@ chunk_free_unchecked(chunk_t *chunk)
   } else {
     if (freelist)
       ++freelist->n_free;
+    tor_assert(total_bytes_allocated_in_chunks >= alloc);
+    total_bytes_allocated_in_chunks -= alloc;
     tor_free(chunk);
   }
 }
@@ -200,6 +207,7 @@ chunk_new_with_alloc_size(size_t alloc)
     else
       ++n_freelist_miss;
     ch = tor_malloc(alloc);
+    total_bytes_allocated_in_chunks += alloc;
   }
   ch->next = NULL;
   ch->datalen = 0;
@@ -211,6 +219,10 @@ chunk_new_with_alloc_size(size_t alloc)
 static void
 chunk_free_unchecked(chunk_t *chunk)
 {
+  if (!chunk)
+    return;
+  tor_assert(total_bytes_allocated_in_chunks >= CHUNK_ALLOC_SIZE(chunk->memlen));
+  total_bytes_allocated_in_chunks -= CHUNK_ALLOC_SIZE(chunk->memlen);
   tor_free(chunk);
 }
 static INLINE chunk_t *
@@ -221,6 +233,7 @@ chunk_new_with_alloc_size(size_t alloc)
   ch->next = NULL;
   ch->datalen = 0;
   ch->memlen = CHUNK_SIZE_WITH_ALLOC(alloc);
+  total_bytes_allocated_in_chunks += alloc;
   ch->data = &ch->mem[0];
   return ch;
 }
@@ -237,6 +250,7 @@ chunk_grow(chunk_t *chunk, size_t sz)
   chunk = tor_realloc(chunk, CHUNK_ALLOC_SIZE(sz));
   chunk->memlen = sz;
   chunk->data = chunk->mem + offset;
+  total_bytes_allocated_in_chunks += (sz - chunk->memlen);
   return chunk;
 }
 
@@ -298,6 +312,8 @@ buf_shrink_freelists(int free_all)
       *chp = NULL;
       while (chunk) {
         chunk_t *next = chunk->next;
+        tor_assert(total_bytes_allocated_in_chunks >= CHUNK_ALLOC_SIZE(chunk->memlen));
+        total_bytes_allocated_in_chunks -= CHUNK_ALLOC_SIZE(chunk->memlen);
         tor_free(chunk);
         chunk = next;
         --n_to_free;
@@ -599,6 +615,7 @@ static chunk_t *
 buf_add_chunk_with_capacity(buf_t *buf, size_t capacity, int capped)
 {
   chunk_t *chunk;
+  struct timeval now;
   if (CHUNK_ALLOC_SIZE(capacity) < buf->default_chunk_size) {
     chunk = chunk_new_with_alloc_size(buf->default_chunk_size);
   } else if (capped && CHUNK_ALLOC_SIZE(capacity) > MAX_CHUNK_ALLOC) {
@@ -606,6 +623,10 @@ buf_add_chunk_with_capacity(buf_t *buf, size_t capacity, int capped)
   } else {
     chunk = chunk_new_with_alloc_size(preferred_chunk_size(capacity));
   }
+
+  tor_gettimeofday_cached(&now);
+  chunk->inserted_time = (uint32_t)tv_to_msec(&now);
+
   if (buf->tail) {
     tor_assert(buf->head);
     buf->tail->next = chunk;
@@ -618,6 +639,26 @@ buf_add_chunk_with_capacity(buf_t *buf, size_t capacity, int capped)
   return chunk;
 }
 
+/** Return the age of the oldest chunk in the buffer <b>buf</b>, in
+ * milliseconds.  Requires the current time, in truncated milliseconds since
+ * the epoch, as its input <b>now</b>.
+ */
+uint32_t
+buf_get_oldest_chunk_timestamp(const buf_t *buf, uint32_t now)
+{
+  if (buf->head) {
+    return now - buf->head->inserted_time;
+  } else {
+    return 0;
+  }
+}
+
+size_t
+buf_get_total_allocation(void)
+{
+  return total_bytes_allocated_in_chunks;
+}
+
 /** Read up to <b>at_most</b> bytes from the socket <b>fd</b> into
  * <b>chunk</b> (which must be on <b>buf</b>). If we get an EOF, set
  * *<b>reached_eof</b> to 1.  Return -1 on error, 0 on eof or blocking,

src/or/buffers.h

@@ -25,6 +25,9 @@ size_t buf_datalen(const buf_t *buf);
 size_t buf_allocation(const buf_t *buf);
 size_t buf_slack(const buf_t *buf);
 
+uint32_t buf_get_oldest_chunk_timestamp(const buf_t *buf, uint32_t now);
+size_t buf_get_total_allocation(void);
+
 int read_to_buf(tor_socket_t s, size_t at_most, buf_t *buf, int *reached_eof,
                 int *socket_error);
 int read_to_buf_tls(tor_tls_t *tls, size_t at_most, buf_t *buf);

src/or/circuitlist.c

@@ -1409,20 +1409,63 @@ circuit_max_queued_cell_age(const circuit_t *c, uint32_t now)
   return age;
 }
 
-/** Temporary variable for circuits_compare_by_oldest_queued_cell_ This is a
- * kludge to work around the fact that qsort doesn't provide a way for
- * comparison functions to take an extra argument. */
-static uint32_t circcomp_now_tmp;
+/** DOCDOC*/
+static uint32_t
+circuit_get_streams_max_data_age(const edge_connection_t *stream, uint32_t now)
+{
+  uint32_t age = 0, age2;
+  for (; stream; stream = stream->next_stream) {
+    const connection_t *conn = TO_CONN(stream);
+    if (conn->outbuf) {
+      age2 = buf_get_oldest_chunk_timestamp(conn->outbuf, now);
+      if (age2 > age)
+        age = age2;
+    }
+    if (conn->inbuf) {
+      age2 = buf_get_oldest_chunk_timestamp(conn->inbuf, now);
+      if (age2 > age)
+        age = age2;
+    }
+  }
 
-/** Helper to sort a list of circuit_t by age of oldest cell, in descending
- * order. Requires that circcomp_now_tmp is set correctly. */
+  return age;
+}
+
+/** DOCDOC
+ */
+static uint32_t
+circuit_max_queued_data_age(const circuit_t *c, uint32_t now)
+{
+  if (CIRCUIT_IS_ORIGIN(c)) {
+    return circuit_get_streams_max_data_age(
+                           TO_ORIGIN_CIRCUIT((circuit_t*)c)->p_streams, now);
+  } else {
+    return circuit_get_streams_max_data_age(
+                           TO_OR_CIRCUIT((circuit_t*)c)->n_streams, now);
+  }
+}
+
+/** DATA */
+static uint32_t
+circuit_max_queued_item_age(const circuit_t *c, uint32_t now)
+{
+  uint32_t cell_age = circuit_max_queued_cell_age(c, now);
+  uint32_t data_age = circuit_max_queued_data_age(c, now);
+  if (cell_age > data_age)
+    return cell_age;
+  else
+    return data_age;
+}
+
+/** Helper to sort a list of circuit_t by age of oldest item, in descending
+ * order. */
 static int
-circuits_compare_by_oldest_queued_cell_(const void **a_, const void **b_)
+circuits_compare_by_oldest_queued_item_(const void **a_, const void **b_)
 {
   const circuit_t *a = *a_;
   const circuit_t *b = *b_;
-  uint32_t age_a = circuit_max_queued_cell_age(a, circcomp_now_tmp);
-  uint32_t age_b = circuit_max_queued_cell_age(b, circcomp_now_tmp);
+  uint32_t age_a = a->age_tmp;
+  uint32_t age_b = b->age_tmp;
 
   if (age_a < age_b)
     return 1;
@@ -1446,6 +1489,7 @@ circuits_handle_oom(size_t current_allocation)
   size_t n_cells_removed=0, n_cells_to_remove;
   int n_circuits_killed=0;
   struct timeval now;
+  uint32_t now_ms;
   log_notice(LD_GENERAL, "We're low on memory.  Killing circuits with "
              "over-long queues. (This behavior is controlled by "
              "MaxMemInCellQueues.)");
@@ -1460,18 +1504,19 @@ circuits_handle_oom(size_t current_allocation)
     n_cells_to_remove = CEIL_DIV(mem_to_recover, packed_cell_mem_cost());
   }
 
+  tor_gettimeofday_cached(&now);
+  now_ms = (uint32_t)tv_to_msec(&now);
+
   /* This algorithm itself assumes that you've got enough memory slack
    * to actually run it. */
-  for (circ = global_circuitlist; circ; circ = circ->next)
+  for (circ = global_circuitlist; circ; circ = circ->next) {
+    circ->age_tmp = circuit_max_queued_item_age(circ, now_ms);
     smartlist_add(circlist, circ);
-
-  /* Set circcomp_now_tmp so that the sort can work. */
-  tor_gettimeofday_cached(&now);
-  circcomp_now_tmp = (uint32_t)tv_to_msec(&now);
+  }
 
   /* This is O(n log n); there are faster algorithms we could use instead.
    * Let's hope this doesn't happen enough to be in the critical path. */
-  smartlist_sort(circlist, circuits_compare_by_oldest_queued_cell_);
+  smartlist_sort(circlist, circuits_compare_by_oldest_queued_item_);
 
   /* Okay, now the worst circuits are at the front of the list. Let's mark
    * them, and reclaim their storage aggressively. */

src/or/or.h

@@ -2564,6 +2564,9 @@ typedef struct circuit_t {
    * more. */
   int deliver_window;
 
+  /** Temporary field used during circuits_handle_oom. */
+  uint32_t age_tmp;
+
   /** For storage while n_conn is pending
     * (state CIRCUIT_STATE_OR_WAIT). When defined, it is always
     * length ONIONSKIN_CHALLENGE_LEN. */

src/or/relay.c

@@ -1998,6 +1998,7 @@ static int
 cell_queues_check_size(void)
 {
   size_t alloc = total_cells_allocated * packed_cell_mem_cost();
+  alloc += buf_get_total_allocation();
   if (alloc >= get_options()->MaxMemInCellQueues) {
     circuits_handle_oom(alloc);
     return 1;