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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libgo/runtime/go-send-nb-small.c | |
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Diffstat (limited to 'libgo/runtime/go-send-nb-small.c')
-rw-r--r-- | libgo/runtime/go-send-nb-small.c | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/libgo/runtime/go-send-nb-small.c b/libgo/runtime/go-send-nb-small.c new file mode 100644 index 000000000..f23ae0164 --- /dev/null +++ b/libgo/runtime/go-send-nb-small.c @@ -0,0 +1,112 @@ +/* go-send-nb-small.c -- nonblocking send of something small on a channel. + + Copyright 2009 The Go Authors. All rights reserved. + Use of this source code is governed by a BSD-style + license that can be found in the LICENSE file. */ + +#include <stdint.h> + +#include "go-assert.h" +#include "go-panic.h" +#include "channel.h" + +/* Prepare to send something on a nonblocking channel. */ + +int +__go_send_nonblocking_acquire (struct __go_channel *channel) +{ + int i; + _Bool has_space; + + i = pthread_mutex_lock (&channel->lock); + __go_assert (i == 0); + + while (channel->selected_for_send) + { + i = pthread_cond_wait (&channel->cond, &channel->lock); + __go_assert (i == 0); + } + + if (channel->is_closed) + { + ++channel->closed_op_count; + if (channel->closed_op_count >= MAX_CLOSED_OPERATIONS) + { + i = pthread_mutex_unlock (&channel->lock); + __go_assert (i == 0); + __go_panic_msg ("too many operations on closed channel"); + } + i = pthread_mutex_unlock (&channel->lock); + __go_assert (i == 0); + return SEND_NONBLOCKING_ACQUIRE_CLOSED; + } + + if (channel->num_entries > 0) + has_space = ((channel->next_store + 1) % channel->num_entries + != channel->next_fetch); + else + { + /* This is a synchronous channel. If somebody is current + sending, then we can't send. Otherwise, see if somebody is + waiting to receive, or see if we can synch with a select. */ + if (channel->waiting_to_send) + { + /* Some other goroutine is currently sending on this + channel, which means that we can't. */ + has_space = 0; + } + else if (channel->waiting_to_receive) + { + /* Some other goroutine is waiting to receive a value, so we + can send directly to them. */ + has_space = 1; + } + else if (__go_synch_with_select (channel, 1)) + { + /* We found a select waiting to receive data, so we can send + to that. */ + __go_broadcast_to_select (channel); + has_space = 1; + } + else + { + /* Otherwise, we can't send, because nobody is waiting to + receive. */ + has_space = 0; + } + + if (has_space) + { + channel->waiting_to_send = 1; + __go_assert (channel->next_store == 0); + } + } + + if (!has_space) + { + i = pthread_mutex_unlock (&channel->lock); + __go_assert (i == 0); + + return SEND_NONBLOCKING_ACQUIRE_NOSPACE; + } + + return SEND_NONBLOCKING_ACQUIRE_SPACE; +} + +/* Send something 64 bits or smaller on a channel. */ + +_Bool +__go_send_nonblocking_small (struct __go_channel *channel, uint64_t val) +{ + __go_assert (channel->element_size <= sizeof (uint64_t)); + + int data = __go_send_nonblocking_acquire (channel); + if (data != SEND_NONBLOCKING_ACQUIRE_SPACE) + return data == SEND_NONBLOCKING_ACQUIRE_CLOSED; + + channel->data[channel->next_store] = val; + + __go_send_release (channel); + + return 1; +} |