Ruby: add performance diagnostic query

Author: asgerf

ruby/ql/src/queries/diagnostics/PerformanceDiagnostics.ql

@@ -0,0 +1,116 @@
+/**
+ * @kind table
+ */
+
+/*
+ *  This query outputs some numbers that can be used to help narrow down the cause of performance
+ *  issues in a codebase, without leaking any actual code or identifiers from the codebase.
+ */
+
+import ruby
+import codeql.ruby.ApiGraphs
+
+query int numberOfModuleBases() { result = count(Ast::ModuleBase cls) }
+
+query int numberOfClasses() { result = count(Ast::ClassDeclaration cls) }
+
+query int numberOfMethods() { result = count(Ast::MethodBase method) }
+
+query int numberOfCallables() { result = count(Ast::Callable c) }
+
+query int numberOfMethodCalls() { result = count(Ast::MethodCall call) }
+
+query int numberOfCalls() { result = count(Ast::Call call) }
+
+signature module HistogramSig {
+  bindingset[this]
+  class Bucket;
+
+  int getCounts(Bucket bucket);
+}
+
+module MakeHistogram<HistogramSig H> {
+  predicate histogram(int bucketSize, int frequency) {
+    frequency = strictcount(H::Bucket bucket | H::getCounts(bucket) = bucketSize)
+  }
+}
+
+module MethodNames implements HistogramSig {
+  class Bucket = string;
+
+  int getCounts(string name) {
+    result = strictcount(Ast::MethodBase method | method.getName() = name) and
+    name != "initialize"
+  }
+}
+
+query predicate numberOfMethodsWithNameHistogram = MakeHistogram<MethodNames>::histogram/2;
+
+module CallTargets implements HistogramSig {
+  class Bucket = Ast::Call;
+
+  int getCounts(Ast::Call call) { result = count(call.getATarget()) }
+}
+
+query predicate numberOfCallTargetsHistogram = MakeHistogram<CallTargets>::histogram/2;
+
+module Callers implements HistogramSig {
+  class Bucket = Ast::Callable;
+
+  int getCounts(Ast::Callable callable) {
+    result = count(Ast::Call call | call.getATarget() = callable)
+  }
+}
+
+query predicate numberOfCallersHistogram = MakeHistogram<Callers>::histogram/2;
+
+private DataFlow::MethodNode getAnOverriddenMethod(DataFlow::MethodNode method) {
+  exists(DataFlow::ModuleNode cls, string name |
+    method = cls.getInstanceMethod(name) and
+    result = cls.getAnAncestor().getInstanceMethod(name) and
+    result != method
+  )
+}
+
+module MethodOverrides implements HistogramSig {
+  class Bucket = DataFlow::MethodNode;
+
+  int getCounts(DataFlow::MethodNode method) { result = count(getAnOverriddenMethod(method)) }
+}
+
+query predicate numberOfOverriddenMethodsHistogram = MakeHistogram<MethodOverrides>::histogram/2;
+
+module MethodOverridenBy implements HistogramSig {
+  class Bucket = DataFlow::MethodNode;
+
+  int getCounts(DataFlow::MethodNode method) {
+    result = count(DataFlow::MethodNode overrider | method = getAnOverriddenMethod(overrider))
+  }
+}
+
+query predicate numberOfOverridingMethodsHistogram = MakeHistogram<MethodOverridenBy>::histogram/2;
+
+module Ancestors implements HistogramSig {
+  class Bucket = DataFlow::ModuleNode;
+
+  int getCounts(DataFlow::ModuleNode mod) {
+    result =
+      count(DataFlow::ModuleNode ancestor | ancestor = mod.getAnAncestor() and ancestor != mod)
+  }
+}
+
+query predicate numberOfAncestorsHistogram = MakeHistogram<Ancestors>::histogram/2;
+
+module Descendents implements HistogramSig {
+  class Bucket = DataFlow::ModuleNode;
+
+  int getCounts(DataFlow::ModuleNode mod) {
+    not mod.getQualifiedName() = ["Object", "Kernel", "BasicObject", "Class", "Module"] and
+    result =
+      count(DataFlow::ModuleNode descendent |
+        descendent = mod.getADescendent() and descendent != mod
+      )
+  }
+}
+
+query predicate numberOfDescendentsHistogram = MakeHistogram<Descendents>::histogram/2;