Core: slab log_nomem flag.

The flag allows to suppress "ngx_slab_alloc() failed: no memory" messages
from a slab allocator, e.g., if an LRU expiration is used by a consumer
and allocation failures aren't fatal.

The flag is now used in the SSL session cache code, and in the limit_req
module.

2 files changed, 7 insertions, 1 deletions

diff --git a/src/core/ngx_slab.c b/src/core/ngx_slab.c
index 6d18abb72..be7927ce0 100644
--- a/src/core/ngx_slab.c
+++ b/src/core/ngx_slab.c
@@ -129,6 +129,7 @@ ngx_slab_init(ngx_slab_pool_t *pool)
         pool->pages->slab = pages;
     }
 
+    pool->log_nomem = 1;
     pool->log_ctx = &pool->zero;
     pool->zero = '\0';
 }
@@ -658,7 +659,10 @@ ngx_slab_alloc_pages(ngx_slab_pool_t *pool, ngx_uint_t pages)
         }
     }
 
-    ngx_slab_error(pool, NGX_LOG_CRIT, "ngx_slab_alloc() failed: no memory");
+    if (pool->log_nomem) {
+        ngx_slab_error(pool, NGX_LOG_CRIT,
+                       "ngx_slab_alloc() failed: no memory");
+    }
 
     return NULL;
 }
diff --git a/src/core/ngx_slab.h b/src/core/ngx_slab.h
index c5e420bfa..5735e3bb3 100644
--- a/src/core/ngx_slab.h
+++ b/src/core/ngx_slab.h
@@ -39,6 +39,8 @@ typedef struct {
     u_char           *log_ctx;
     u_char            zero;
 
+    unsigned          log_nomem:1;
+
     void             *data;
     void             *addr;
 } ngx_slab_pool_t;