Ruby/performance queries

ruby/ql/lib/codeql/ruby/frameworks/ActiveRecord.qll

@@ -352,8 +352,7 @@
 }
 
 // A call to `find`, `where`, etc. that may return active record model object(s)
-private class ActiveRecordModelFinderCall extends ActiveRecordModelInstantiation, DataFlow::CallNode
-{
+class ActiveRecordModelFinderCall extends ActiveRecordModelInstantiation, DataFlow::CallNode {
   private ActiveRecordModelClass cls;
 
   ActiveRecordModelFinderCall() {

ruby/ql/src/queries/performance/CouldBeAsync.qhelp

@@ -0,0 +1,24 @@
+<!DOCTYPE qhelp PUBLIC
+  "-//Semmle//qhelp//EN"
+  "qhelp.dtd">
+<qhelp>
+
+<overview>
+<p>
+When an AcriveRecord query is executed synchronously, the application is blocked until the query completes. This can lead to poor performance, especially when the query is slow or when many queries are executed in sequence. This query identifies ActiveRecord queries that could be executed asynchronously to improve performance.
+Specifically, this query identifies ActiveRecord queries that are executed in a loop. If each query is independent of the others, the queries could be executed in parallel by using the built-in Ruby <code>load_async</code> method.
+In those cases, where the query includes a <code>pluck</code> call, the query could be executed asynchronously by using the <code>async_pluck</code> method.
+</p>
+</overview>
+<recommendation>
+<p>If possible, split the loop into two. The first creates a map of promises resolving to the async query results. The second runs throuhg this map, waiting on each promise, and does whatever the original loop did with the result of the query.</p>
+</recommendation>
+<example>
+<p>The following (suboptimal) example code executes a series of ActiveRecord queries in a loop. The queries are independent of each other, so they could be executed in parallel to improve performance.</p>
+<sample src="examples/straight_loop.rb" />
+<p>To be able to fetch the necessary information asynchronously, we first pull it out into its own (implicit) loop:
+<sample src="examples/preload.rb" />
+<p>We can now use the <code>async_pluck</code> method to execute the queries in parallel.</p>
+<sample src="examples/async_pluck.rb" />
+</example>
+</qhelp>

ruby/ql/src/queries/performance/CouldBeAsync.ql

@@ -0,0 +1,93 @@
+/**
+ * @name Could be async
+ * @description Use `ActiveRecord::Relation#load_async` to load records asynchronously.
+ * @kind problem
+ * @problem.severity info
+ * @precision high
+ * @id rb/could-be-async
+ * @tags performance
+ */
+
+import ruby
+private import codeql.ruby.AST
+import codeql.ruby.Concepts
+import codeql.ruby.frameworks.ActiveRecord
+private import codeql.ruby.TaintTracking
+
+string loopMethodName() {
+  result in [
+      "each", "reverse_each", "map", "map!", "foreach", "flat_map", "in_batches", "one?", "all?",
+      "collect", "collect!", "select", "select!", "reject", "reject!"
+    ]
+}
+
+class LoopingCall extends DataFlow::CallNode {
+  DataFlow::CallableNode loopBlock;
+
+  LoopingCall() {
+    this.getMethodName() = loopMethodName() and loopBlock = this.getBlock().asCallable()
+  }
+
+  DataFlow::CallableNode getLoopBlock() { result = loopBlock }
+}
+
+predicate happensInLoop(LoopingCall loop, DataFlow::CallNode e) {
+  loop.getLoopBlock().asCallableAstNode() = e.asExpr().getScope()
+}
+
+predicate happensInOuterLoop(LoopingCall outerLoop, DataFlow::CallNode e) {
+  exists(LoopingCall innerLoop |
+    happensInLoop(outerLoop, innerLoop) and
+    happensInLoop(innerLoop, e)
+  )
+}
+
+predicate happensInInnermostLoop(LoopingCall loop, DataFlow::CallNode e) {
+  happensInLoop(loop, e) and
+  not happensInOuterLoop(loop, e)
+}
+
+private class PluckCall extends ActiveRecordInstanceMethodCall {
+  PluckCall() { this.getMethodName() in ["pluck"] }
+
+  ActiveRecordInstance chaines() { result = getChain(this) }
+}
+
+private ActiveRecordInstance getChain(ActiveRecordInstanceMethodCall c) {
+  result = c.getInstance()
+  or
+  result = getChain(c.getInstance())
+}
+
+// The ActiveRecord instance is used to potentially control the loop
+predicate usedInLoopControlGuard(ActiveRecordInstance ar, DataFlow::Node guard) {
+  TaintTracking::localTaint(ar, guard) and
+  guard = guardForLoopControl(_, _)
+}
+
+// A guard for controlling the loop
+DataFlow::Node guardForLoopControl(ConditionalExpr cond, Stmt control) {
+  result.asExpr().getAstNode() = cond.getCondition().getAChild*() and
+  (
+    control.(MethodCall).getMethodName() = "raise"
+    or
+    control instanceof NextStmt
+  ) and
+  control = cond.getBranch(_).getAChild()
+}
+
+from LoopingCall loop, DataFlow::CallNode call, string message
+where
+  not call.getLocation().getFile().getAbsolutePath().matches("%test%") and
+  not call = any(PluckCall p).chaines() and
+  not usedInLoopControlGuard(call, _) and
+  happensInInnermostLoop(loop, call) and
+  (
+    call instanceof ActiveRecordModelFinderCall and
+    not call.getMethodName() in ["new", "create"] and
+    message = "could be chained with load_async"
+    or
+    call instanceof PluckCall and
+    message = "could be async_pluck"
+  )
+select call, "This call happens inside $@, and " + message, loop, "this loop"

ruby/ql/src/queries/performance/examples/async_pluck.rb

@@ -0,0 +1,16 @@
+require 'async_pluck'
+
+# Preload User data in parallel
+user_data = User.where(login: repo_names_by_owner.keys).async_pluck(:login, :id, :type).to_h do |login, id, type|
+  [login, { id: id, type: type == "User" ? "USER" : "ORGANIZATION" }]
+end
+
+repo_names_by_owner.each do |owner_slug, repo_names|
+  owner_info = user_data[owner_slug]
+  owner_id = owner_info[:id]
+  owner_type = owner_info[:type]
+  rel_conditions = { owner_id: owner_id, name: repo_names }
+
+  nwo_rel = nwo_rel.or(RepositorySecurityCenterConfig.where(rel_conditions)) unless neg
+  nwo_rel = nwo_rel.and(RepositorySecurityCenterConfig.where.not(rel_conditions)) if neg
+end

ruby/ql/src/queries/performance/examples/preload.rb

@@ -0,0 +1,14 @@
+# Preload User data
+user_data = User.where(login: repo_names_by_owner.keys).pluck(:login, :id, :type).to_h do |login, id, type|
+    [login, { id: id, type: type == "User" ? "USER" : "ORGANIZATION" }]
+  end
+
+  repo_names_by_owner.each do |owner_slug, repo_names|
+    owner_info = user_data[owner_slug]
+    owner_id = owner_info[:id]
+    owner_type = owner_info[:type]
+    rel_conditions = { owner_id: owner_id, name: repo_names }
+
+    nwo_rel = nwo_rel.or(RepositorySecurityCenterConfig.where(rel_conditions)) unless neg
+    nwo_rel = nwo_rel.and(RepositorySecurityCenterConfig.where.not(rel_conditions)) if neg
+  end

ruby/ql/src/queries/performance/examples/straight_loop.rb

@@ -0,0 +1,8 @@
+repo_names_by_owner.map do |owner_slug, repo_names|
+    owner_id, owner_type = User.where(login: owner_slug).pluck(:id, :type).first
+    owner_type = owner_type == "User" ? "USER" : "ORGANIZATION"
+    rel_conditions = { owner_id: owner_id, name: repo_names }
+
+    nwo_rel = nwo_rel.or(RepositorySecurityCenterConfig.where(rel_conditions)) unless neg
+    nwo_rel = nwo_rel.and(RepositorySecurityCenterConfig.where.not(rel_conditions)) if neg
+  end