Initial unit tests for OOM handling

src/test/include.am

@@ -32,6 +32,7 @@ src_test_test_SOURCES = \
 	src/test/test_introduce.c \
 	src/test/test_logging.c \
 	src/test/test_microdesc.c \
+	src/test/test_oom.c \
 	src/test/test_options.c \
 	src/test/test_pt.c \
 	src/test/test_replay.c \

src/test/test.c

@@ -1627,6 +1627,7 @@ extern struct testcase_t logging_tests[];
 extern struct testcase_t backtrace_tests[];
 extern struct testcase_t hs_tests[];
 extern struct testcase_t nodelist_tests[];
+extern struct testcase_t oom_tests[];
 
 static struct testgroup_t testgroups[] = {
   { "", test_array },
@@ -1652,6 +1653,7 @@ static struct testgroup_t testgroups[] = {
   { "control/", controller_event_tests },
   { "hs/", hs_tests },
   { "nodelist/", nodelist_tests },
+  { "oom/", oom_tests },
   END_OF_GROUPS
 };
 

src/test/test_oom.c

@@ -0,0 +1,199 @@
+/* Copyright (c) 2014, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/* Unit tests for OOM handling logic */
+
+#define RELAY_PRIVATE
+#define BUFFERS_PRIVATE
+#define CIRCUITLIST_PRIVATE
+#include "or.h"
+#include "buffers.h"
+#include "circuitlist.h"
+#include "compat_libevent.h"
+#include "connection.h"
+#include "config.h"
+#include "mempool.h"
+#include "relay.h"
+#include "test.h"
+
+/* small replacement mock for circuit_mark_for_close_ to avoid doing all
+ * the other bookkeeping that comes with marking circuits. */
+static void
+circuit_mark_for_close_dummy_(circuit_t *circ, int reason, int line,
+                              const char *file)
+{
+  (void) reason;
+  if (circ->marked_for_close) {
+    TT_FAIL(("Circuit already marked for close at %s:%d, but we are marking "
+             "it again at %s:%d",
+             circ->marked_for_close_file, (int)circ->marked_for_close,
+             file, line));
+  }
+
+  circ->marked_for_close = line;
+  circ->marked_for_close_file = file;
+}
+
+static circuit_t *
+dummy_or_circuit_new(int n_p_cells, int n_n_cells)
+{
+  or_circuit_t *circ = or_circuit_new(0, NULL);
+  int i;
+  cell_t cell;
+
+  for (i=0; i < n_p_cells; ++i) {
+    crypto_rand((void*)&cell, sizeof(cell));
+    cell_queue_append_packed_copy(TO_CIRCUIT(circ), &circ->p_chan_cells,
+                                  0, &cell, 1, 0);
+  }
+
+  for (i=0; i < n_n_cells; ++i) {
+    crypto_rand((void*)&cell, sizeof(cell));
+    cell_queue_append_packed_copy(TO_CIRCUIT(circ),
+                                  &TO_CIRCUIT(circ)->n_chan_cells,
+                                  1, &cell, 1, 0);
+  }
+
+  TO_CIRCUIT(circ)->purpose = CIRCUIT_PURPOSE_OR;
+  return TO_CIRCUIT(circ);
+}
+
+static circuit_t *
+dummy_origin_circuit_new(int n_cells)
+{
+  origin_circuit_t *circ = origin_circuit_new();
+  int i;
+  cell_t cell;
+
+  for (i=0; i < n_cells; ++i) {
+    crypto_rand((void*)&cell, sizeof(cell));
+    cell_queue_append_packed_copy(TO_CIRCUIT(circ),
+                                  &TO_CIRCUIT(circ)->n_chan_cells,
+                                  1, &cell, 1, 0);
+  }
+
+  TO_CIRCUIT(circ)->purpose = CIRCUIT_PURPOSE_C_GENERAL;
+  return TO_CIRCUIT(circ);
+}
+
+#if 0
+static void
+add_bytes_to_buf(generic_buffer_t *buf, size_t n_bytes)
+{
+  char b[3000];
+
+  while (n_bytes) {
+    size_t this_add = n_bytes > sizeof(buf) ? sizeof(buf) : n_bytes;
+    crypto_rand(b, sizeof(b));
+    generic_buffer_add(buf, b, this_add);
+    n_bytes -= this_add;
+  }
+}
+
+static edge_connection_t *
+dummy_edge_conn_new(int type, size_t in_bytes, size_t out_bytes)
+{
+  edge_connection_t *conn = edge_connection_new(type, AF_INET);
+
+  /* We add these bytes directly to the buffers, to avoid all the
+   * edge connection read/write machinery. */
+  add_bytes_to_buf(TO_CONN(conn)->inbuf, in_bytes);
+  add_bytes_to_buf(TO_CONN(conn)->outbuf, out_bytes);
+
+  return conn;
+}
+#endif
+
+/** Run unit tests for buffers.c */
+static void
+test_oom_circbuf(void *arg)
+{
+  or_options_t *options = get_options_mutable();
+  circuit_t *c1 = NULL, *c2 = NULL, *c3 = NULL, *c4 = NULL;
+  struct timeval tv = { 1389631048, 0 };
+
+  (void) arg;
+
+  MOCK(circuit_mark_for_close_, circuit_mark_for_close_dummy_);
+  init_cell_pool();
+
+  /* Far too low for real life. */
+  options->MaxMemInQueues = 256*packed_cell_mem_cost();
+  options->CellStatistics = 0;
+
+  tt_int_op(cell_queues_check_size(), ==, 0); /* We don't start out OOM. */
+  tt_int_op(cell_queues_get_total_allocation(), ==, 0);
+  tt_int_op(buf_get_total_allocation(), ==, 0);
+
+  /* Now we're going to fake up some circuits and get them added to the global
+     circuit list. */
+  tv.tv_usec = 0;
+  tor_gettimeofday_cache_set(&tv);
+  c1 = dummy_origin_circuit_new(30);
+  tv.tv_usec = 10*1000;
+  tor_gettimeofday_cache_set(&tv);
+  c2 = dummy_or_circuit_new(20, 20);
+
+  tt_int_op(packed_cell_mem_cost(), ==,
+            sizeof(packed_cell_t) + MP_POOL_ITEM_OVERHEAD);
+  tt_int_op(cell_queues_get_total_allocation(), ==,
+            packed_cell_mem_cost() * 70);
+  tt_int_op(cell_queues_check_size(), ==, 0); /* We are still not OOM */
+
+  tv.tv_usec = 20*1000;
+  tor_gettimeofday_cache_set(&tv);
+  c3 = dummy_or_circuit_new(100, 85);
+  tt_int_op(cell_queues_check_size(), ==, 0); /* We are still not OOM */
+  tt_int_op(cell_queues_get_total_allocation(), ==,
+            packed_cell_mem_cost() * 255);
+
+  tv.tv_usec = 30*1000;
+  tor_gettimeofday_cache_set(&tv);
+  /* Adding this cell will trigger our OOM handler. */
+  c4 = dummy_or_circuit_new(2, 0);
+
+  tt_int_op(cell_queues_get_total_allocation(), ==,
+            packed_cell_mem_cost() * 257);
+
+  tt_int_op(cell_queues_check_size(), ==, 1); /* We are now OOM */
+
+  tt_assert(c1->marked_for_close);
+  tt_assert(! c2->marked_for_close);
+  tt_assert(! c3->marked_for_close);
+  tt_assert(! c4->marked_for_close);
+
+  tt_int_op(cell_queues_get_total_allocation(), ==,
+            packed_cell_mem_cost() * (257 - 30));
+
+  circuit_free(c1);
+  tv.tv_usec = 0;
+  tor_gettimeofday_cache_set(&tv); /* go back in time */
+  c1 = dummy_or_circuit_new(90, 0);
+
+  tv.tv_usec = 40*1000; /* go back to the future */
+  tor_gettimeofday_cache_set(&tv);
+
+  tt_int_op(cell_queues_check_size(), ==, 1); /* We are now OOM */
+
+  tt_assert(c1->marked_for_close);
+  tt_assert(! c2->marked_for_close);
+  tt_assert(! c3->marked_for_close);
+  tt_assert(! c4->marked_for_close);
+
+  tt_int_op(cell_queues_get_total_allocation(), ==,
+            packed_cell_mem_cost() * (257 - 30));
+
+ done:
+  circuit_free(c1);
+  circuit_free(c2);
+  circuit_free(c3);
+  circuit_free(c4);
+
+  UNMOCK(circuit_mark_for_close_);
+}
+
+struct testcase_t oom_tests[] = {
+  { "circbuf", test_oom_circbuf, TT_FORK, NULL, NULL },
+  END_OF_TESTCASES
+};
+