From 466e8a923cc2d84c4b0557484cadd7f03d724661 Mon Sep 17 00:00:00 2001
From: Johan Wikman <johan.wikman@mariadb.com>
Date: Tue, 31 Jul 2018 09:44:41 +0300
Subject: [PATCH] MXS-1992 Handle 'query_classifier_cache_size' parameter

No effect yet on the caching.
---
 include/maxscale/query_classifier.h |  1 +
 server/core/config.cc               | 14 +++++++++++---
 server/core/query_classifier.cc     | 23 +++++++++++++----------
 3 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/include/maxscale/query_classifier.h b/include/maxscale/query_classifier.h
index c7f3d1a07..dbd4aa5a3 100644
--- a/include/maxscale/query_classifier.h
+++ b/include/maxscale/query_classifier.h
@@ -439,6 +439,7 @@ typedef struct query_classifier
  */
 typedef struct QC_CACHE_PROPERTIES
 {
+    int64_t max_size;  /** The maximum size of the cache. */
 } QC_CACHE_PROPERTIES;
 
 /**
diff --git a/server/core/config.cc b/server/core/config.cc
index 21bec653f..ca957afa7 100644
--- a/server/core/config.cc
+++ b/server/core/config.cc
@@ -127,7 +127,7 @@ const char CN_PORT[]                          = "port";
 const char CN_PROTOCOL[]                      = "protocol";
 const char CN_QUERY_CLASSIFIER[]              = "query_classifier";
 const char CN_QUERY_CLASSIFIER_ARGS[]         = "query_classifier_args";
-const char CN_QUERY_CLASSIFIER_CACHE[]        = "query_classifier_cache";
+const char CN_QUERY_CLASSIFIER_CACHE_SIZE[]   = "query_classifier_cache_size";
 const char CN_QUERY_RETRIES[]                 = "query_retries";
 const char CN_QUERY_RETRY_TIMEOUT[]           = "query_retry_timeout";
 const char CN_RELATIONSHIPS[]                 = "relationships";
@@ -2119,9 +2119,17 @@ handle_global_item(const char *name, const char *value)
     {
         gateway.qc_args = MXS_STRDUP_A(value);
     }
-    else if (strcmp(name, CN_QUERY_CLASSIFIER_CACHE) == 0)
+    else if (strcmp(name, CN_QUERY_CLASSIFIER_CACHE_SIZE) == 0)
     {
-        static QC_CACHE_PROPERTIES cache_properties;
+        static QC_CACHE_PROPERTIES cache_properties = { INT64_MAX };
+
+        cache_properties.max_size = get_suffixed_size(value);
+
+        if (cache_properties.max_size < 0)
+        {
+            // Someone got carried away; we'll just silently adjust the value.
+            cache_properties.max_size = INT64_MAX;
+        }
 
         gateway.qc_cache_properties = &cache_properties;
     }
diff --git a/server/core/query_classifier.cc b/server/core/query_classifier.cc
index 28e0d126d..ab6b46104 100644
--- a/server/core/query_classifier.cc
+++ b/server/core/query_classifier.cc
@@ -12,6 +12,7 @@
  */
 
 #include "internal/query_classifier.h"
+#include <inttypes.h>
 #include <algorithm>
 #include <unordered_map>
 #include <maxscale/alloc.h>
@@ -51,13 +52,13 @@ static struct this_unit
     QUERY_CLASSIFIER*    classifier;
     qc_trx_parse_using_t qc_trx_parse_using;
     qc_sql_mode_t        qc_sql_mode;
-    int32_t              use_cached_result;
+    int64_t              cache_max_size;
 } this_unit =
 {
-    nullptr,
-    QC_TRX_PARSE_USING_PARSER,
-    QC_SQL_MODE_DEFAULT,
-    1  // TODO: Make this configurable
+    nullptr,                   // classifier
+    QC_TRX_PARSE_USING_PARSER, // qc_trx_parse_using
+    QC_SQL_MODE_DEFAULT,       // qc_sql_mode
+    INT64_MAX                  // cache_max_size; TODO: Make this configurable
 };
 
 class QCInfoCache;
@@ -178,7 +179,7 @@ private:
 
 bool use_cached_result()
 {
-    return atomic_load_int32(&this_unit.use_cached_result) != 0;
+    return atomic_load_int64(&this_unit.cache_max_size) != 0;
 }
 
 bool has_not_been_parsed(GWBUF* pStmt)
@@ -279,18 +280,20 @@ bool qc_setup(const QC_CACHE_PROPERTIES* cache_properties,
         {
             this_unit.qc_sql_mode = sql_mode;
 
-            bool use_cached_result = (cache_properties != nullptr);
+            int64_t cache_max_size = (cache_properties ? cache_properties->max_size : 0);
+            ss_dassert(cache_max_size >= 0);
 
-            if (use_cached_result)
+            if (cache_max_size)
             {
-                MXS_NOTICE("Query classification results are cached and reused.");
+                MXS_NOTICE("Query classification results are cached and reused, "
+                           "cache max size: %" PRIi64 "", cache_max_size);
             }
             else
             {
                 MXS_NOTICE("Query classification results are not cached.");
             }
 
-            this_unit.use_cached_result = use_cached_result;
+            this_unit.cache_max_size = cache_max_size;
         }
         else
         {