[core] shared temp buffer for log_*error*()

use shared temp buffer for preparing error log entries
(each error log entry is flushed to error log;
 there is no persistent data buffering for error logs)

src/configfile.c

@@ -1560,6 +1560,7 @@ int config_log_error_open(server *srv) {
                  * prior to set_defaults hook, and modules should not save a
                  * pointer to srv->errh until set_defaults hook or later)*/
                 p->defaults.errh = srv->errh = fdlog;
+                log_set_global_errh(srv->errh);
                 fdlog_free(errh);
             }
             cpv->v.v = errh = fdlog;

src/log.c

@@ -23,6 +23,8 @@
 #include "ck.h"
 #include "fdlog.h"
 
+static buffer *errh_b;
+
 /* log_con_jqueue instance here to be defined in shared object (see base.h) */
 connection *log_con_jqueue;
 
@@ -163,7 +165,7 @@ log_buffer_vprintf (buffer * const b,
 {
     /* NOTE: log_buffer_prepare() ensures 0 != b->used */
     /*assert(0 != b->used);*//*(only because code calcs below assume this)*/
-    /*assert(0 != b->size);*//*(errh->b should not have 0 size here)*/
+    /*assert(0 != b->size);*//*(b has non-size after log_buffer_prepare())*/
     size_t blen = buffer_clen(b);
     size_t bsp  = buffer_string_space(b)+1;
     char *s = b->ptr + blen;
@@ -214,7 +216,7 @@ log_error_va_list_impl (log_error_st * const errh,
                         const int perr)
 {
     const int errnum = errno;
-    buffer * const b = &errh->b;
+    buffer * const b = errh_b ? errh_b : &errh->b;
     if (-1 == log_buffer_prepare(errh, filename, line, b)) return;
     log_buffer_vprintf(b, fmt, ap);
     if (perr)
@@ -259,7 +261,7 @@ log_error_multiline (log_error_st * const restrict errh,
     if (0 == len) return;
 
     const int errnum = errno;
-    buffer * const b = &errh->b;
+    buffer * const b = errh_b ? errh_b : &errh->b;
     if (-1 == log_buffer_prepare(errh, filename, line, b)) return;
 
     va_list ap;
@@ -283,3 +285,10 @@ log_error_multiline (log_error_st * const restrict errh,
 
     errno = errnum;
 }
+
+
+void
+log_set_global_errh (log_error_st * const errh)
+{
+    errh_b = errh ? &errh->b : NULL;
+}

src/log.h

@@ -30,4 +30,7 @@ __attribute_cold__
 __attribute_format__((__printf__, 6, 7))
 void log_error_multiline(log_error_st *errh, const char *filename, unsigned int line, const char * restrict multiline, const size_t len, const char *fmt, ...);
 
+__attribute_cold__
+void log_set_global_errh (log_error_st *errh);
+
 #endif

src/server.c

@@ -308,6 +308,7 @@ static server *server_init(void) {
 	log_monotonic_secs = server_monotonic_secs();
 
 	srv->errh = fdlog_init(NULL, STDERR_FILENO, FDLOG_FD);
+	log_set_global_errh(srv->errh);
 
 	config_init(srv);
 
@@ -352,6 +353,7 @@ static void server_free(server *srv) {
 	li_rand_cleanup();
 	chunkqueue_chunk_pool_free();
 
+	log_set_global_errh(NULL);
 	fdlog_free(srv->errh);
 	free(srv);
 }