Speed optimizations. Merged 3 writes into 1.

Got rid of std::string construction.
More unification on syslog,stderr,fd.

Signed-off-by: Adam Kupczyk <akupczyk@mirantis.com>

src/common/PrebufferedStreambuf.cc

@@ -1,6 +1,6 @@
 
 #include "common/PrebufferedStreambuf.h"
-
+#include <string.h>
 PrebufferedStreambuf::PrebufferedStreambuf(char *buf, size_t len)
   : m_buf(buf), m_buf_len(len)
 {
@@ -61,3 +61,42 @@ std::string PrebufferedStreambuf::get_str() const
     return std::string(m_buf, this->pptr() - m_buf);
   }  
 }
+// returns current size of content
+size_t PrebufferedStreambuf::size() const
+{
+  if(m_overflow.size() == 0) {
+    return this->pptr() - m_buf;
+  } else {
+    return m_buf_len + this->pptr() - &m_overflow[0];
+  }
+}
+
+// extracts up to avail chars of content
+int PrebufferedStreambuf::snprintf(char* dst, size_t avail) const
+{
+  size_t o_size = m_overflow.size();
+  size_t len_a;
+  size_t len_b;
+  if(o_size>0){
+    len_a = m_buf_len;
+    len_b = this->pptr() - &m_overflow[0];
+  } else {
+    len_a = this->pptr() - m_buf;
+    len_b = 0;
+  }
+  if(avail > len_a + len_b) {
+    memcpy(dst, m_buf, len_a);
+    memcpy(dst + m_buf_len, m_overflow.c_str(), len_b);
+    dst[len_a + len_b] = 0;
+  } else {
+    if(avail > len_a) {
+      memcpy(dst, m_buf, len_a);
+      memcpy(dst + m_buf_len, m_overflow.c_str(), avail - len_a - 1);
+      dst[avail - 1] = 0;
+    } else {
+      memcpy(dst, m_buf, avail - 1);
+      dst[avail - 1] = 0;
+    }
+  }
+  return len_a + len_b;
+}

src/common/PrebufferedStreambuf.h

@@ -37,6 +37,12 @@ class PrebufferedStreambuf
 
   /// return a string copy (inefficiently)
   std::string get_str() const;
-};    
+
+  // returns current size of content
+  size_t size() const;
+
+  // extracts up to avail chars of content
+  int snprintf(char* dst, size_t avail) const;
+};
 
 #endif

src/include/utime.h

@@ -239,12 +239,22 @@ class utime_t {
     time_t tt = sec();
     localtime_r(&tt, &bdt);
 
-    return snprintf(out, outlen,
+    return ::snprintf(out, outlen,
 		    "%04d-%02d-%02d %02d:%02d:%02d.%06ld",
 		    bdt.tm_year + 1900, bdt.tm_mon + 1, bdt.tm_mday,
 		    bdt.tm_hour, bdt.tm_min, bdt.tm_sec, usec());
   }
 
+  static int snprintf(char *out, int outlen, time_t tt) {
+    struct tm bdt;
+    localtime_r(&tt, &bdt);
+
+    return ::snprintf(out, outlen,
+        "%04d-%02d-%02d %02d:%02d:%02d",
+        bdt.tm_year + 1900, bdt.tm_mon + 1, bdt.tm_mday,
+        bdt.tm_hour, bdt.tm_min, bdt.tm_sec);
+  }
+
   static int parse_date(const string& date, uint64_t *epoch, uint64_t *nsec,
                         string *out_date=NULL, string *out_time=NULL) {
     struct tm tm;

src/log/Entry.h

@@ -48,6 +48,16 @@ struct Entry {
   std::string get_str() const {
     return m_streambuf.get_str();
   }
+
+  // returns current size of content
+  size_t size() const {
+    return m_streambuf.size();
+  }
+
+  // extracts up to avail chars of content
+  int snprintf(char* dst, size_t avail) const {
+    return m_streambuf.snprintf(dst, avail);
+  }
 };
 
 }

src/log/Log.cc

@@ -209,7 +209,6 @@ void Log::flush()
 void Log::_flush(EntryQueue *t, EntryQueue *requeue, bool crash)
 {
   Entry *e;
-  char buf[80];
   while ((e = t->dequeue()) != NULL) {
     unsigned sub = e->m_subsys;
 
@@ -219,33 +218,33 @@ void Log::_flush(EntryQueue *t, EntryQueue *requeue, bool crash)
     bool do_stderr = m_stderr_crash >= e->m_prio && should_log;
 
     if (do_fd || do_syslog || do_stderr) {
-      int buflen = 0;
+      size_t buflen = 0;
+      char buf[80 + e->size()];
 
       if (crash)
 	buflen += snprintf(buf, sizeof(buf), "%6d> ", -t->m_len);
       buflen += e->m_stamp.sprintf(buf + buflen, sizeof(buf)-buflen);
       buflen += snprintf(buf + buflen, sizeof(buf)-buflen, " %lx %2d ",
 			(unsigned long)e->m_thread, e->m_prio);
 
-      // FIXME: this is slow
-      string s = e->get_str();
-
-      if (do_fd) {
-	int r = safe_write(m_fd, buf, buflen);
-	if (r >= 0)
-	  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;
+      buflen += e->snprintf(buf + buflen, sizeof(buf) - buflen - 1);
+      if(buflen > sizeof(buf) - 1) { //paranoid check, buf was declared to hold everything
+        buflen = sizeof(buf) - 1;
+        buf[buflen] = 0;
       }
 
       if (do_syslog) {
-	syslog(LOG_USER, "%s%s", buf, s.c_str());
+        syslog(LOG_USER, "%s", buf);
       }
 
       if (do_stderr) {
-	cerr << buf << s << std::endl;
+        cerr << buf << std::endl;
+      }
+      if (do_fd) {
+        buf[buflen] = '\n';
+        int r = safe_write(m_fd, buf, buflen+1);
+        if (r < 0)
+          cerr << "problem writing to " << m_log_file << ": " << cpp_strerror(r) << std::endl;
       }
     }