TS-2005: bug fix: now can support big cluster
when the writer aborted, the reader just read from cache.
set HTTP_NO_KEEPALIVE before abort when EOS
for cop_test_page, not open_read from cluster.
for cop_test_page, just open_write in local mode.
TS-2005: bug fix: now can support big cluster for session alloc
TS-2191 not reschedule the http_sm when not acquired the sm_list`s lock.
TS-2197 http_sm may not perceive client_vc`s aborted if it is not a new connection.
TS-2201
TS-2202: remove manager error and fatal useless errno and error message

we should log errno and strerror(errno) only when errno != 0.
the errno parameter should pass by the caller.
initialize the first_dir and earliest_dir to empty when we read from writer.
TS-2187: use nonblock eventfd in EventNotify

1) Use nonblock eventfd, so that we can tolerate write() failed with
   errno EAGAIN – which is acceptable as the signal receiver will be
   notified eventually in this case.

2) After using nonblock eventfd, read() will not block in wait(). So
   I use epoll_wait() to implement block behavior, just like timedwait().

3) nonblock eventfd can fix a potential problem: if receiver didn't
   read() data immediately, senders might block in write().

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>
TS-2187: Fix return in EventNotify::wait()

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>
cluster prev writer allocated.

Change-Id: If9467f1fb1743e978ac5ee9554c35d6ce7ca395a
fix the a few bugs.

Change-Id: I9dbc521bfffee99fc9251a7d609009a141f69b0f
1) the stats of cachevc is negative.
2) the crash for CLUSTER_INTERNEL_ERROR for the first response of cache read.
3) for Cache-Control of no_cache, remove the alternate.
add a config that make the read not delay too long if the writer
have no response.
fix the build error of previous commit.
TS-2220
add cache url convert API for plugin

function prototype:
  TSRemapStatus _tsremap_convert_cache_url(void* ih, const RemapUrlInfo
     *old_url, RemapUrlInfo *new_url);

adding API:
   TSReturnCode TSCacheUrlGet(const char *in_url, const int in_url_len,
     char *out_url, const int out_size, int *out_url_len);
TS-2232: log level should be change from Status to Debug