diff options
Diffstat (limited to 'src/or/scheduler_vanilla.c')
| -rw-r--r-- | src/or/scheduler_vanilla.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/src/or/scheduler_vanilla.c b/src/or/scheduler_vanilla.c new file mode 100644 index 0000000000..303b3dbba8 --- /dev/null +++ b/src/or/scheduler_vanilla.c @@ -0,0 +1,197 @@ +/* Copyright (c) 2017, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +#include <event2/event.h> + +#include "or.h" +#include "config.h" +#define TOR_CHANNEL_INTERNAL_ +#include "channel.h" +#define SCHEDULER_PRIVATE_ +#include "scheduler.h" + +/***************************************************************************** + * Other internal data + *****************************************************************************/ + +/* Maximum cells to flush in a single call to channel_flush_some_cells(); */ +#define MAX_FLUSH_CELLS 1000 + +/***************************************************************************** + * Externally called function implementations + *****************************************************************************/ + +/* Return true iff the scheduler has work to perform. */ +static int +have_work(void) +{ + smartlist_t *cp = get_channels_pending(); + IF_BUG_ONCE(!cp) { + return 0; // channels_pending doesn't exist so... no work? + } + return smartlist_len(cp) > 0; +} + +/** Re-trigger the scheduler in a way safe to use from the callback */ + +static void +vanilla_scheduler_schedule(void) +{ + if (!have_work()) { + return; + } + + /* Activate our event so it can process channels. */ + scheduler_ev_active(EV_TIMEOUT); +} + +static void +vanilla_scheduler_run(void) +{ + int n_cells, n_chans_before, n_chans_after; + ssize_t flushed, flushed_this_time; + smartlist_t *cp = get_channels_pending(); + smartlist_t *to_readd = NULL; + channel_t *chan = NULL; + + log_debug(LD_SCHED, "We have a chance to run the scheduler"); + + n_chans_before = smartlist_len(cp); + + while (smartlist_len(cp) > 0) { + /* Pop off a channel */ + chan = smartlist_pqueue_pop(cp, + scheduler_compare_channels, + offsetof(channel_t, sched_heap_idx)); + IF_BUG_ONCE(!chan) { + /* Some-freaking-how a NULL got into the channels_pending. That should + * never happen, but it should be harmless to ignore it and keep looping. + */ + continue; + } + + /* Figure out how many cells we can write */ + n_cells = channel_num_cells_writeable(chan); + if (n_cells > 0) { + log_debug(LD_SCHED, + "Scheduler saw pending channel " U64_FORMAT " at %p with " + "%d cells writeable", + U64_PRINTF_ARG(chan->global_identifier), chan, n_cells); + + flushed = 0; + while (flushed < n_cells) { + flushed_this_time = + channel_flush_some_cells(chan, + MIN(MAX_FLUSH_CELLS, (size_t) n_cells - flushed)); + if (flushed_this_time <= 0) break; + flushed += flushed_this_time; + } + + if (flushed < n_cells) { + /* We ran out of cells to flush */ + chan->scheduler_state = SCHED_CHAN_WAITING_FOR_CELLS; + log_debug(LD_SCHED, + "Channel " U64_FORMAT " at %p " + "entered waiting_for_cells from pending", + U64_PRINTF_ARG(chan->global_identifier), + chan); + } else { + /* The channel may still have some cells */ + if (channel_more_to_flush(chan)) { + /* The channel goes to either pending or waiting_to_write */ + if (channel_num_cells_writeable(chan) > 0) { + /* Add it back to pending later */ + if (!to_readd) to_readd = smartlist_new(); + smartlist_add(to_readd, chan); + log_debug(LD_SCHED, + "Channel " U64_FORMAT " at %p " + "is still pending", + U64_PRINTF_ARG(chan->global_identifier), + chan); + } else { + /* It's waiting to be able to write more */ + chan->scheduler_state = SCHED_CHAN_WAITING_TO_WRITE; + log_debug(LD_SCHED, + "Channel " U64_FORMAT " at %p " + "entered waiting_to_write from pending", + U64_PRINTF_ARG(chan->global_identifier), + chan); + } + } else { + /* No cells left; it can go to idle or waiting_for_cells */ + if (channel_num_cells_writeable(chan) > 0) { + /* + * It can still accept writes, so it goes to + * waiting_for_cells + */ + chan->scheduler_state = SCHED_CHAN_WAITING_FOR_CELLS; + log_debug(LD_SCHED, + "Channel " U64_FORMAT " at %p " + "entered waiting_for_cells from pending", + U64_PRINTF_ARG(chan->global_identifier), + chan); + } else { + /* + * We exactly filled up the output queue with all available + * cells; go to idle. + */ + chan->scheduler_state = SCHED_CHAN_IDLE; + log_debug(LD_SCHED, + "Channel " U64_FORMAT " at %p " + "become idle from pending", + U64_PRINTF_ARG(chan->global_identifier), + chan); + } + } + } + + log_debug(LD_SCHED, + "Scheduler flushed %d cells onto pending channel " + U64_FORMAT " at %p", + (int)flushed, U64_PRINTF_ARG(chan->global_identifier), + chan); + } else { + log_info(LD_SCHED, + "Scheduler saw pending channel " U64_FORMAT " at %p with " + "no cells writeable", + U64_PRINTF_ARG(chan->global_identifier), chan); + /* Put it back to WAITING_TO_WRITE */ + chan->scheduler_state = SCHED_CHAN_WAITING_TO_WRITE; + } + } + + /* Readd any channels we need to */ + if (to_readd) { + SMARTLIST_FOREACH_BEGIN(to_readd, channel_t *, readd_chan) { + readd_chan->scheduler_state = SCHED_CHAN_PENDING; + smartlist_pqueue_add(cp, + scheduler_compare_channels, + offsetof(channel_t, sched_heap_idx), + readd_chan); + } SMARTLIST_FOREACH_END(readd_chan); + smartlist_free(to_readd); + } + + n_chans_after = smartlist_len(cp); + log_debug(LD_SCHED, "Scheduler handled %d of %d pending channels", + n_chans_before - n_chans_after, n_chans_before); +} + +/* Stores the vanilla scheduler function pointers. */ +static scheduler_t vanilla_scheduler = { + .type = SCHEDULER_VANILLA, + .free_all = NULL, + .on_channel_free = NULL, + .init = NULL, + .on_new_consensus = NULL, + .schedule = vanilla_scheduler_schedule, + .run = vanilla_scheduler_run, + .on_new_options = NULL, +}; + +scheduler_t * +get_vanilla_scheduler(void) +{ + return &vanilla_scheduler; +} + |