v1/topdown/graphql: Cache GraphQL schema parse results (open-policy-agent#5377)

This commit stores parsed GraphQL schemas to the cache, which improves
the performance of GraphQL operations that parse the schema more than once.

Queries are not cached.

BenchmarkGraphQLSchemaIsValid/Trivial_Schema_-_string-10	         	   23740	     51418 ns/op
BenchmarkGraphQLSchemaIsValid/Trivial_Schema_with_cache_-_string-10         	  965624	      1187 ns/op
BenchmarkGraphQLSchemaIsValid/Schema_w/_1000_types_-_string-10              	     751	   1578718 ns/op
BenchmarkGraphQLSchemaIsValid/Schema_w/_1000_types_with_cache_-_string-10   	   33801	     34915 ns/op
BenchmarkGraphQLSchemaIsValid/Trivial_Schema_-_AST_object-10                	   17491	     67845 ns/op
BenchmarkGraphQLSchemaIsValid/Trivial_Schema_with_cache_-_AST_object-10     	  124808	      9801 ns/op
BenchmarkGraphQLParseSchema/Trivial_Schema_-_string-10                      	    9914	    116169 ns/op
BenchmarkGraphQLParseSchema/Trivial_Schema_with_cache_-_string-10           	  678207	      1640 ns/op
BenchmarkGraphQLParseQuery/Trivial_Query_-_string-10                        	   26994	     44328 ns/op
BenchmarkGraphQLParseQuery/Trivial_Query_with_cache_-_string-10             	   26922	     44386 ns/op
BenchmarkGraphQLIsValid/Trivial_Schema_-_string-10                          	   21441	     55487 ns/op
BenchmarkGraphQLIsValid/Trivial_Schema_with_cache_-_string-10               	  152800	      7384 ns/op
BenchmarkGraphQLIsValid/Schema_w/_1000_types_-_string-10                    	     758	   1568036 ns/op
BenchmarkGraphQLIsValid/Schema_w/_1000_types_with_cache_-_string-10         	   28108	     43051 ns/op
BenchmarkGraphQLParse/Trivial_Schema_-_string-10                            	    5119	    216610 ns/op
BenchmarkGraphQLParse/Trivial_Schema_with_cache_-_string-10                 	   24186	     49551 ns/op
BenchmarkGraphQLParseAndVerify/Trivial_Schema_-_string-10                   	    5241	    217419 ns/op
BenchmarkGraphQLParseAndVerify/Trivial_Schema_with_cache_-_string-10        	   23911	     50004 ns/op

Resolves: open-policy-agent#5377

Signed-off-by: Rob Myers <[email protected]>

Author: robmyersrobmyers

Diff for: docs/content/configuration.md

@@ -863,17 +863,19 @@ Caching represents the configuration of the inter-query cache that built-in func
 functions provided by OPA, `http.send` is currently the only one to utilize the inter-query cache. See the documentation
 on the [http.send built-in function](../policy-reference/#http) for information about the available caching options.
 
-It also represents the configuration of the inter-query _value_ cache that built-in functions can utilize. Currently, 
+It also represents the configuration of the inter-query _value_ cache that built-in functions can utilize. Currently,
 this cache is utilized by the `regex` and `glob` built-in functions for compiled regex and glob match patterns
-respectively, and the `json.schema_match` built-in function for compiled JSON schemas.
+respectively, the `json.schema_match` built-in function for compiled JSON schemas, and any `graphql` built-in function
+that requires GraphQL schemas.
 
 | Field                                                                    | Type    | Required | Description                                                                                                                                                                                                                                          |
 |--------------------------------------------------------------------------|---------|----------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | `caching.inter_query_builtin_cache.max_size_bytes`                       | `int64` | No       | Inter-query cache size limit in bytes. OPA will drop old items from the cache if this limit is exceeded. By default, no limit is set.                                                                                                                |
-| `caching.inter_query_builtin_cache.forced_eviction_threshold_percentage` | `int64` | No       | Threshold limit configured as percentage of `caching.inter_query_builtin_cache.max_size_bytes`, when exceeded OPA will start dropping old items permaturely. By default, set to `100`.                                                               |
+| `caching.inter_query_builtin_cache.forced_eviction_threshold_percentage` | `int64` | No       | Threshold limit configured as percentage of `caching.inter_query_builtin_cache.max_size_bytes`, when exceeded OPA will start dropping old items prematurely. By default, set to `100`.                                                               |
 | `caching.inter_query_builtin_cache.stale_entry_eviction_period_seconds`  | `int64` | No       | Stale entry eviction period in seconds. OPA will drop expired items from the cache every `stale_entry_eviction_period_seconds`. By default, set to `0` indicating stale entry eviction is disabled.                                                  |
 | `caching.inter_query_builtin_value_cache.max_num_entries`                | `int`   | No       | Maximum number of entries in the Inter-query value cache. OPA will drop random items from the cache if this limit is exceeded. By default, set to `0` indicating unlimited size.                                                                     |
 | `caching.inter_query_builtin_value_cache.named.io_jwt.max_num_entries`   | `int`   | No       | Maximum number of entries in the `io_jwt` cache, used by the [`io.jwt` token verification](../policy-reference/#tokens) built-in functions. OPA will drop random items from the cache if this limit is exceeded. By default, this cache is disabled. |
+| `caching.inter_query_builtin_value_cache.named.graphql.max_num_entries`  | `int`   | No       | Maximum number of entries in the `graphql` cache, used by the [`graphql` builtins](../policy-reference/#graphql) built-in functions to cache parsed schemas. OPA will drop random items from the cache if this limit is exceeded. By default, this cache is set to a maximum of 10 entries. |
 
 ## Distributed tracing
 

Diff for: v1/plugins/discovery/discovery_test.go

@@ -1721,8 +1721,9 @@ func TestReconfigureWithLocalOverride(t *testing.T) {
 			"inter_query_builtin_cache": {"max_size_bytes": 10000000, "forced_eviction_threshold_percentage": 90},
 			"inter_query_builtin_value_cache": {
 				"named": {
-					"io_jwt": {"max_num_entries": 55}
-				} 
+					"io_jwt": {"max_num_entries": 55},
+					"graphql": {"max_num_entries": 10}
+				}
 			}
 		}
 	}`)
@@ -1888,8 +1889,9 @@ func TestReconfigureWithLocalOverride(t *testing.T) {
 					"inter_query_builtin_cache": {"max_size_bytes": 200, "stale_entry_eviction_period_seconds": 10, "forced_eviction_threshold_percentage": 200},
 					"inter_query_builtin_value_cache": {
 						"named": {
-							"io_jwt": {"max_num_entries": 10}
-						} 
+							"io_jwt": {"max_num_entries": 10},
+							"graphql": {"max_num_entries": 11}
+						}
 					}
 				}
 			}
@@ -1906,6 +1908,7 @@ func TestReconfigureWithLocalOverride(t *testing.T) {
 		"caching.inter_query_builtin_cache.max_size_bytes",
 		"caching.inter_query_builtin_cache.forced_eviction_threshold_percentage",
 		"caching.inter_query_builtin_value_cache.named.io_jwt.max_num_entries",
+		"caching.inter_query_builtin_value_cache.named.graphql.max_num_entries",
 	}
 	for _, k := range expectedOverriddenKeys {
 		if !strings.Contains(disco.status.Message, k) {
@@ -1928,6 +1931,8 @@ func TestReconfigureWithLocalOverride(t *testing.T) {
 	*maxNumEntriesInterQueryValueCache = 0
 	maxNumEntriesJWTValueCache := new(int)
 	*maxNumEntriesJWTValueCache = 55
+	maxNumEntriesGraphQLValueCache := new(int)
+	*maxNumEntriesGraphQLValueCache = 10
 
 	expectedCacheConf := &cache.Config{
 		InterQueryBuiltinCache: cache.InterQueryBuiltinCacheConfig{
@@ -1941,6 +1946,9 @@ func TestReconfigureWithLocalOverride(t *testing.T) {
 				"io_jwt": {
 					MaxNumEntries: maxNumEntriesJWTValueCache,
 				},
+				"graphql": {
+					MaxNumEntries: maxNumEntriesGraphQLValueCache,
+				},
 			},
 		},
 	}