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StateEventLogger.cc
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StateEventLogger.cc
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/** @file
A brief file description
@section license License
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements. See the NOTICE file
distributed with this work for additional information
regarding copyright ownership. The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#include "ink_unused.h" /* MAGIC_EDITING_TAG */
#include "StateEventLogger.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#ifdef USE_RINGBUF
/*
* two situations: . = data. d_next== d_free is empty
* d_next d_free "A"
* v...............v
*
* d_free d_next v (d_len-1) "B"
* ......v v.........
* d_len points off the end of the array
*/
RingBuf::RingBuf(int len)
{
d_buf = (char *) calloc(1, len + 1);
d_len = len + 1;
d_free = 0;
d_next = 0;
}
RingBuf::~RingBuf()
{
xfree(d_buf);
}
int
RingBuf::avail()
{
if (d_next <= d_free) {
return d_free - d_next; // "A"
} else {
return (d_len - d_next + d_free);
}
}
// for length 1 array
//
//
int
RingBuf::free()
{
if (d_next <= d_free) {
return (d_next + d_len - d_free - 1); // "A"
} else {
return (d_next - d_free - 1);
}
}
int
RingBuf::append(char *buf, int len)
{
int towrite = min(len, free());
if (d_next <= d_free) {
int wrote = 0;
while (d_free<d_len && towrite> 0) {
d_buf[d_free] = *buf;
buf++;
towrite--;
d_free++;
wrote++;
}
// fell off end of array or source buf
if (d_free == d_len) {
d_free = 0;
}
while (d_free<(d_next - 1) && towrite> 0) {
d_buf[d_free] = *buf;
buf++;
towrite--;
d_free++;
wrote++;
}
// we always have a free space
assert(d_free != d_next);
return wrote;
} else {
int wrote = 0;
while (d_free<d_next && towrite> 0) {
d_buf[d_free] = *buf;
buf++;
towrite--;
d_free++;
wrote++;
}
// fell off end of array or source buf
// we always have a free space
assert(d_free != d_next);
return wrote;
}
}
int
RingBuf::flush(int d_fd, int len)
{
int toflush = min(len, avail());
int nflushed = 0;
if (d_next <= d_free) {
if (d_next<d_free && toflush> 0) {
int w = min(d_free - d_next, toflush);
write(d_fd, &d_buf[d_next], w);
nflushed = w;
d_next += w;
toflush -= w;
}
assert(toflush == 0);
return (nflushed);
} else {
if (d_next<d_len && toflush> 0) {
int w = min(d_len - d_next, toflush);
write(d_fd, &d_buf[d_next], w);
d_next += w;
nflushed = w;
toflush -= w;
}
if (d_next == d_len) {
d_next = 0;
}
if (d_next<d_free && toflush> 0) {
int w = min(d_free - d_next, toflush);
write(d_fd, &d_buf[d_next], w);
d_next += w;
nflushed += w;
toflush -= w;
}
assert(toflush == 0);
return (nflushed);
}
}
#ifdef TEST_RINGBUF
#define test(x) \
if (!(x)) { \
printf (# x " failed\n"); \
}
int
main()
{
RingBuf m(1);
char buf[2];
test(m.avail() == 0);
test(m.free() == 1);
test(m.append("b", 2) == 1);
test(m.avail() == 1);
test(m.free() == 0);
test(m.flush(0, 2) == 1); // write to stdout
//test(buf[0]=='b');
}
#endif
#endif /* USE_RINGBUF */
StateEvent::~StateEvent()
{
}
#ifdef USE_RINGBUF
void
StateEventLogger::operator () (const StateEvent & x)
{
if (d_fd < 0) {
return;
}
// try lock d_buf head pointer
if (ink_mutex_try_acquire(&d_head_lock)) {
// if lock taken and
if (d_buf->avail() > d_highwater) {
// flush buffer & update head pointer
d_buf->flush(d_fd, d_buf->avail());
}
// if locked unlock d_buf head pointer
ink_mutex_release(&d_head_lock);
}
// if lock failed, we could be writing to the end of the buffer,
// even while another thread is flushing the buffer.
// lock d_buf tail pointer
if (ink_mutex_acquire(&d_tail_lock)) {
if (x.size() < d_buf->free()) {
x.marshal(d_buf);
} else {
// this is bad too.
assert(0);
}
// unlock d_buf tail pointer
ink_mutex_release(&d_tail_lock);
} else {
assert(0); // this should never happen
}
}
#else
void
StateEventLogger::operator () (const StateEvent & x)
{
if (d_fd < 0) {
return;
}
char buf[12];
x.marshal(buf);
write(d_fd, buf, x.size());
}
#endif
#ifdef TEST_STATELOGGER
#define test(x) \
if (!(x)) { \
printf (# x " failed\n"); \
}
TestStateEvent x;
StateEventLogger *sel;
#define N_THREADS 10
void *
test_thread(void *i)
{
int pi = (int) i;
int j;
int calls = 70000;
ink_hrtime start, finish;
start = ink_get_hrtime();
for (j = 0; j < calls; j++) {
(*sel) (TestStateEvent(pi, j));
}
#ifdef __alpha
#define LL_FMT "%ld"
#else
#define LL_FMT "%lld"
#endif
finish = ink_get_hrtime();
printf("StateEventLogger cost = " LL_FMT "ns\n", (finish - start) / (N_THREADS * calls));
return NULL;
}
int
main()
{
// create some threads.
int i;
ink_thread t[N_THREADS];
sel = NEW(new StateEventLogger("sel.out"));
for (i = 0; i < N_THREADS; i++) {
t[i] = ink_thread_create(test_thread, (void *) i);
}
for (i = 0; i < N_THREADS; i++) {
ink_thread_join(t[i]);
}
// check that output is not garbled
// actually just print out the cost of calling this function:
delete sel;
}
#endif