Merge branch 'bug9093_023' into maint-0.2.3

This commit is contained in:
Nick Mathewson 2013-11-15 15:23:51 -05:00
commit 9e90707602
4 changed files with 64 additions and 12 deletions

7
changes/bug9093 Normal file
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@ -0,0 +1,7 @@
o Minor features:
- Improve the circuit queue out-of-memory handler. Previously, when
we ran low on memory, we'd close whichever circuits had the most
queued cells. Now, we close those that have the *oldest* queued
cells, on the theory that those are most responsible for us
running low on memory. Based on analysis from a forthcoming paper
by Jansen, Tschorsch, Johnson, and Scheuermann. Fixes bug 9093.

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@ -1383,25 +1383,56 @@ n_cells_in_circ_queues(const circuit_t *c)
return n;
}
/** helper to sort a list of circuit_q by total queue lengths, in descending
* order. */
/**
* Return the age of the oldest cell queued on <b>c</b>, in milliseconds.
* Return 0 if there are no cells queued on c. Requires that <b>now</b> be
* the current time in milliseconds since the epoch, truncated.
*
* This function will return incorrect results if the oldest cell queued on
* the circuit is older than 2**32 msec (about 49 days) old.
*/
static uint32_t
circuit_max_queued_cell_age(const circuit_t *c, uint32_t now)
{
uint32_t age = 0;
if (c->n_conn_cells.head)
age = now - c->n_conn_cells.head->inserted_time;
if (! CIRCUIT_IS_ORIGIN(c)) {
const or_circuit_t *orcirc = TO_OR_CIRCUIT((circuit_t*)c);
if (orcirc->p_conn_cells.head) {
uint32_t age2 = now - orcirc->p_conn_cells.head->inserted_time;
if (age2 > age)
return age2;
}
}
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;
/** Helper to sort a list of circuit_t by age of oldest cell, in descending
* order. Requires that circcomp_now_tmp is set correctly. */
static int
circuits_compare_by_queue_len_(const void **a_, const void **b_)
circuits_compare_by_oldest_queued_cell_(const void **a_, const void **b_)
{
const circuit_t *a = *a_;
const circuit_t *b = *b_;
size_t a_n = n_cells_in_circ_queues(a);
size_t b_n = n_cells_in_circ_queues(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);
if (a_n < b_n)
if (age_a < age_b)
return 1;
else if (a_n == b_n)
else if (age_a == age_b)
return 0;
else
return -1;
}
#define FRACTION_OF_CIRCS_TO_RETAIN_ON_OOM 0.90
#define FRACTION_OF_CELLS_TO_RETAIN_ON_OOM 0.90
/** We're out of memory for cells, having allocated <b>current_allocation</b>
* bytes' worth. Kill the 'worst' circuits until we're under
@ -1414,13 +1445,14 @@ circuits_handle_oom(size_t current_allocation)
circuit_t *circ;
size_t n_cells_removed=0, n_cells_to_remove;
int n_circuits_killed=0;
struct timeval now;
log_notice(LD_GENERAL, "We're low on memory. Killing circuits with "
"over-long queues. (This behavior is controlled by "
"MaxMemInCellQueues.)");
{
size_t mem_target = (size_t)(get_options()->MaxMemInCellQueues *
FRACTION_OF_CIRCS_TO_RETAIN_ON_OOM);
FRACTION_OF_CELLS_TO_RETAIN_ON_OOM);
size_t mem_to_recover;
if (current_allocation <= mem_target)
return;
@ -1433,9 +1465,13 @@ circuits_handle_oom(size_t current_allocation)
for (circ = global_circuitlist; circ; circ = circ->next)
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_queue_len_);
smartlist_sort(circlist, circuits_compare_by_oldest_queued_cell_);
/* Okay, now the worst circuits are at the front of the list. Let's mark
* them, and reclaim their storage aggressively. */

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@ -912,8 +912,13 @@ typedef struct var_cell_t {
typedef struct packed_cell_t {
struct packed_cell_t *next; /**< Next cell queued on this circuit. */
char body[CELL_NETWORK_SIZE]; /**< Cell as packed for network. */
uint32_t inserted_time; /**< Time (in milliseconds since epoch, with high
* bits truncated) when this cell was inserted. */
} packed_cell_t;
/* XXXX This next structure may be obsoleted by inserted_time in
* packed_cell_t */
/** Number of cells added to a circuit queue including their insertion
* time on 10 millisecond detail; used for buffer statistics. */
typedef struct insertion_time_elem_t {

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@ -1904,15 +1904,19 @@ cell_queue_append(cell_queue_t *queue, packed_cell_t *cell)
void
cell_queue_append_packed_copy(cell_queue_t *queue, const cell_t *cell)
{
packed_cell_t *copy = packed_cell_copy(cell);
/* Remember the time when this cell was put in the queue. */
if (get_options()->CellStatistics) {
struct timeval now;
packed_cell_t *copy = packed_cell_copy(cell);
tor_gettimeofday_cached(&now);
copy->inserted_time = (uint32_t)tv_to_msec(&now);
/* Remember the time when this cell was put in the queue. */
/*XXXX This may be obsoleted by inserted_time */
if (get_options()->CellStatistics) {
uint32_t added;
insertion_time_queue_t *it_queue = queue->insertion_times;
if (!it_pool)
it_pool = mp_pool_new(sizeof(insertion_time_elem_t), 1024);
tor_gettimeofday_cached(&now);
#define SECONDS_IN_A_DAY 86400L
added = (uint32_t)(((now.tv_sec % SECONDS_IN_A_DAY) * 100L)
+ ((uint32_t)now.tv_usec / (uint32_t)10000L));