log: do not repeat errors to stderr

If we get an error writing to the log, log it only once to stderr.
This avoids generating, say, 72 GB of ENOSPC errors in
teuthology.log when /var/log fills up.

Fixes: #14616
Signed-off-by: Sage Weil <sage@redhat.com>
(cherry picked from commit d9ac0474b864afda58a44b9012cca4bbc6aaf509)

Conflicts:
	src/log/Log.cc (drop m_uid and m_gid which are not used in hammer;
	order of do_stderr, do_syslog, do_fd conditional blocks is reversed in
	hammer; drop irrelevant speed optimization code from
	5bfe05aebfefdff9022f0eb990805758e0edb1dc)

diff --git a/src/log/Log.cc b/src/log/Log.cc
index a3e54dfa61bff9c1ccf73515fdcb9527fabd7d82..075f917360793bb359247b516a9d10e78e7ae5df 100644 (file)
--- a/src/log/Log.cc
+++ b/src/log/Log.cc
@@ -41,6 +41,7 @@ Log::Log(SubsystemMap *s)
     m_flush_mutex_holder(0),
     m_new(), m_recent(),
     m_fd(-1),
+    m_fd_last_error(0),
     m_syslog_log(-2), m_syslog_crash(-2),
     m_stderr_log(1), m_stderr_crash(-1),
     m_stop(false),
@@ -236,8 +237,13 @@ void Log::_flush(EntryQueue *t, EntryQueue *requeue, bool crash)
          r = safe_write(m_fd, s.data(), s.size());
        if (r >= 0)
          r = write(m_fd, "\n", 1);
-       if (r < 0)
-         cerr << "problem writing to " << m_log_file << ": " << cpp_strerror(r) << std::endl;
+       if (r != m_fd_last_error) {
+         if (r < 0)
+           cerr << "problem writing to " << m_log_file
+                << ": " << cpp_strerror(r)
+                << std::endl;
+         m_fd_last_error = r;
+       }
       }
 
       if (do_syslog) {

diff --git a/src/log/Log.h b/src/log/Log.h
index 04cadd726f68db344568288f652f7224c98f7556..efa520f89e22588151f3925e24f90144770db705 100644 (file)
--- a/src/log/Log.h
+++ b/src/log/Log.h
@@ -35,6 +35,8 @@ class Log : private Thread
   std::string m_log_file;
   int m_fd;
 
+  int m_fd_last_error;  ///< last error we say writing to fd (if any)
+
   int m_syslog_log, m_syslog_crash;
   int m_stderr_log, m_stderr_crash;