diff options
Diffstat (limited to 'src/core/ext/filters/max_age/max_age_filter.cc')
| -rw-r--r-- | src/core/ext/filters/max_age/max_age_filter.cc | 180 |
1 files changed, 159 insertions, 21 deletions
diff --git a/src/core/ext/filters/max_age/max_age_filter.cc b/src/core/ext/filters/max_age/max_age_filter.cc index 7b86e4cd6c..a3f9780f3f 100644 --- a/src/core/ext/filters/max_age/max_age_filter.cc +++ b/src/core/ext/filters/max_age/max_age_filter.cc @@ -37,6 +37,12 @@ #define MAX_CONNECTION_IDLE_INTEGER_OPTIONS \ { DEFAULT_MAX_CONNECTION_IDLE_MS, 1, INT_MAX } +/* States for idle_state in channel_data */ +#define MAX_IDLE_STATE_INIT ((gpr_atm)0) +#define MAX_IDLE_STATE_SEEN_EXIT_IDLE ((gpr_atm)1) +#define MAX_IDLE_STATE_SEEN_ENTER_IDLE ((gpr_atm)2) +#define MAX_IDLE_STATE_TIMER_SET ((gpr_atm)3) + namespace { struct channel_data { /* We take a reference to the channel stack for the timer callback */ @@ -64,7 +70,7 @@ struct channel_data { grpc_millis max_connection_age_grace; /* Closure to run when the channel's idle duration reaches max_connection_idle and should be closed gracefully */ - grpc_closure close_max_idle_channel; + grpc_closure max_idle_timer_cb; /* Closure to run when the channel reaches its max age and should be closed gracefully */ grpc_closure close_max_age_channel; @@ -85,26 +91,117 @@ struct channel_data { grpc_connectivity_state connectivity_state; /* Number of active calls */ gpr_atm call_count; + /* TODO(zyc): C++lize this state machine */ + /* 'idle_state' holds the states of max_idle_timer and channel idleness. + It can contain one of the following values: + +--------------------------------+----------------+---------+ + | idle_state | max_idle_timer | channel | + +--------------------------------+----------------+---------+ + | MAX_IDLE_STATE_INIT | unset | busy | + | MAX_IDLE_STATE_TIMER_SET | set, valid | idle | + | MAX_IDLE_STATE_SEEN_EXIT_IDLE | set, invalid | busy | + | MAX_IDLE_STATE_SEEN_ENTER_IDLE | set, invalid | idle | + +--------------------------------+----------------+---------+ + + MAX_IDLE_STATE_INIT: The initial and final state of 'idle_state'. The + channel has 1 or 1+ active calls, and the the timer is not set. Note that + we may put a virtual call to hold this state at channel initialization or + shutdown, so that the channel won't enter other states. + + MAX_IDLE_STATE_TIMER_SET: The state after the timer is set and no calls + have arrived after the timer is set. The channel must have 0 active call in + this state. If the timer is fired in this state, we will close the channel + due to idleness. + + MAX_IDLE_STATE_SEEN_EXIT_IDLE: The state after the timer is set and at + least one call has arrived after the timer is set. The channel must have 1 + or 1+ active calls in this state. If the timer is fired in this state, we + won't reschudle it. + + MAX_IDLE_STATE_SEEN_ENTER_IDLE: The state after the timer is set and the at + least one call has arrived after the timer is set, BUT the channel + currently has 1 or 1+ active calls. If the timer is fired in this state, we + will reschudle it. + + max_idle_timer will not be cancelled (unless the channel is shutting down). + If the timer callback is called when the max_idle_timer is valid (i.e. + idle_state is MAX_IDLE_STATE_TIMER_SET), the channel will be closed due to + idleness, otherwise the channel won't be changed. + + State transitions: + MAX_IDLE_STATE_INIT <-------3------ MAX_IDLE_STATE_SEEN_EXIT_IDLE + ^ | ^ ^ | + | | | | | + 1 2 +-----------4------------+ 6 7 + | | | | | + | v | | v + MAX_IDLE_STATE_TIMER_SET <----5------ MAX_IDLE_STATE_SEEN_ENTER_IDLE + + For 1, 3, 5 : See max_idle_timer_cb() function + For 2, 7 : See decrease_call_count() function + For 4, 6 : See increase_call_count() function */ + gpr_atm idle_state; + /* Time when the channel finished its last outstanding call, in grpc_millis */ + gpr_atm last_enter_idle_time_millis; }; } // namespace /* Increase the nubmer of active calls. Before the increasement, if there are no calls, the max_idle_timer should be cancelled. */ static void increase_call_count(channel_data* chand) { + /* Exit idle */ if (gpr_atm_full_fetch_add(&chand->call_count, 1) == 0) { - grpc_timer_cancel(&chand->max_idle_timer); + while (true) { + gpr_atm idle_state = gpr_atm_acq_load(&chand->idle_state); + switch (idle_state) { + case MAX_IDLE_STATE_TIMER_SET: + /* max_idle_timer_cb may have already set idle_state to + MAX_IDLE_STATE_INIT, in this case, we don't need to set it to + MAX_IDLE_STATE_SEEN_EXIT_IDLE */ + gpr_atm_rel_cas(&chand->idle_state, MAX_IDLE_STATE_TIMER_SET, + MAX_IDLE_STATE_SEEN_EXIT_IDLE); + return; + case MAX_IDLE_STATE_SEEN_ENTER_IDLE: + gpr_atm_rel_store(&chand->idle_state, MAX_IDLE_STATE_SEEN_EXIT_IDLE); + return; + default: + /* try again */ + break; + } + } } } /* Decrease the nubmer of active calls. After the decrement, if there are no calls, the max_idle_timer should be started. */ static void decrease_call_count(channel_data* chand) { + /* Enter idle */ if (gpr_atm_full_fetch_add(&chand->call_count, -1) == 1) { - GRPC_CHANNEL_STACK_REF(chand->channel_stack, "max_age max_idle_timer"); - grpc_timer_init( - &chand->max_idle_timer, - grpc_core::ExecCtx::Get()->Now() + chand->max_connection_idle, - &chand->close_max_idle_channel); + gpr_atm_no_barrier_store(&chand->last_enter_idle_time_millis, + (gpr_atm)grpc_core::ExecCtx::Get()->Now()); + while (true) { + gpr_atm idle_state = gpr_atm_acq_load(&chand->idle_state); + switch (idle_state) { + case MAX_IDLE_STATE_INIT: + GRPC_CHANNEL_STACK_REF(chand->channel_stack, + "max_age max_idle_timer"); + grpc_timer_init( + &chand->max_idle_timer, + grpc_core::ExecCtx::Get()->Now() + chand->max_connection_idle, + &chand->max_idle_timer_cb); + gpr_atm_rel_store(&chand->idle_state, MAX_IDLE_STATE_TIMER_SET); + return; + case MAX_IDLE_STATE_SEEN_EXIT_IDLE: + if (gpr_atm_rel_cas(&chand->idle_state, MAX_IDLE_STATE_SEEN_EXIT_IDLE, + MAX_IDLE_STATE_SEEN_ENTER_IDLE)) { + return; + } + break; + default: + /* try again */ + break; + } + } } } @@ -152,20 +249,58 @@ static void start_max_age_grace_timer_after_goaway_op(void* arg, "max_age start_max_age_grace_timer_after_goaway_op"); } -static void close_max_idle_channel(void* arg, grpc_error* error) { +static void close_max_idle_channel(channel_data* chand) { + /* Prevent the max idle timer from being set again */ + gpr_atm_no_barrier_fetch_add(&chand->call_count, 1); + grpc_transport_op* op = grpc_make_transport_op(nullptr); + op->goaway_error = + grpc_error_set_int(GRPC_ERROR_CREATE_FROM_STATIC_STRING("max_idle"), + GRPC_ERROR_INT_HTTP2_ERROR, GRPC_HTTP2_NO_ERROR); + grpc_channel_element* elem = + grpc_channel_stack_element(chand->channel_stack, 0); + elem->filter->start_transport_op(elem, op); +} + +static void max_idle_timer_cb(void* arg, grpc_error* error) { channel_data* chand = (channel_data*)arg; if (error == GRPC_ERROR_NONE) { - /* Prevent the max idle timer from being set again */ - gpr_atm_no_barrier_fetch_add(&chand->call_count, 1); - grpc_transport_op* op = grpc_make_transport_op(nullptr); - op->goaway_error = - grpc_error_set_int(GRPC_ERROR_CREATE_FROM_STATIC_STRING("max_idle"), - GRPC_ERROR_INT_HTTP2_ERROR, GRPC_HTTP2_NO_ERROR); - grpc_channel_element* elem = - grpc_channel_stack_element(chand->channel_stack, 0); - elem->filter->start_transport_op(elem, op); - } else if (error != GRPC_ERROR_CANCELLED) { - GRPC_LOG_IF_ERROR("close_max_idle_channel", error); + bool try_again = true; + while (try_again) { + gpr_atm idle_state = gpr_atm_acq_load(&chand->idle_state); + switch (idle_state) { + case MAX_IDLE_STATE_TIMER_SET: + close_max_idle_channel(chand); + /* This MAX_IDLE_STATE_INIT is a final state, we don't have to check + * if idle_state has been changed */ + gpr_atm_rel_store(&chand->idle_state, MAX_IDLE_STATE_INIT); + try_again = false; + break; + case MAX_IDLE_STATE_SEEN_EXIT_IDLE: + if (gpr_atm_rel_cas(&chand->idle_state, MAX_IDLE_STATE_SEEN_EXIT_IDLE, + MAX_IDLE_STATE_INIT)) { + try_again = false; + } + break; + case MAX_IDLE_STATE_SEEN_ENTER_IDLE: + GRPC_CHANNEL_STACK_REF(chand->channel_stack, + "max_age max_idle_timer"); + grpc_timer_init(&chand->max_idle_timer, + (grpc_millis)gpr_atm_no_barrier_load( + &chand->last_enter_idle_time_millis) + + chand->max_connection_idle, + &chand->max_idle_timer_cb); + /* idle_state may have already been set to + MAX_IDLE_STATE_SEEN_EXIT_IDLE by increase_call_count(), in this + case, we don't need to set it to MAX_IDLE_STATE_TIMER_SET */ + gpr_atm_rel_cas(&chand->idle_state, MAX_IDLE_STATE_SEEN_ENTER_IDLE, + MAX_IDLE_STATE_TIMER_SET); + try_again = false; + break; + default: + /* try again */ + break; + } + } } GRPC_CHANNEL_STACK_UNREF(chand->channel_stack, "max_age max_idle_timer"); } @@ -288,6 +423,9 @@ static grpc_error* init_channel_elem(grpc_channel_element* elem, chand->max_connection_idle = DEFAULT_MAX_CONNECTION_IDLE_MS == INT_MAX ? GRPC_MILLIS_INF_FUTURE : DEFAULT_MAX_CONNECTION_IDLE_MS; + chand->idle_state = MAX_IDLE_STATE_INIT; + gpr_atm_no_barrier_store(&chand->last_enter_idle_time_millis, + GRPC_MILLIS_INF_PAST); for (size_t i = 0; i < args->channel_args->num_args; ++i) { if (0 == strcmp(args->channel_args->args[i].key, GRPC_ARG_MAX_CONNECTION_AGE_MS)) { @@ -311,8 +449,8 @@ static grpc_error* init_channel_elem(grpc_channel_element* elem, value == INT_MAX ? GRPC_MILLIS_INF_FUTURE : value; } } - GRPC_CLOSURE_INIT(&chand->close_max_idle_channel, close_max_idle_channel, - chand, grpc_schedule_on_exec_ctx); + GRPC_CLOSURE_INIT(&chand->max_idle_timer_cb, max_idle_timer_cb, chand, + grpc_schedule_on_exec_ctx); GRPC_CLOSURE_INIT(&chand->close_max_age_channel, close_max_age_channel, chand, grpc_schedule_on_exec_ctx); GRPC_CLOSURE_INIT(&chand->force_close_max_age_channel, |