make skipFunctions, onlyFunctions, and specialForms as ExpressionFuzz…

…er options.

Summary:
More refactoring for the expression fuzzer.

1) Push the skipFunctions, onlyFunctions, and specialForms as ExpressionFuzzer options.
2) FuzzerRunner: just a tool that wrap ExpressionFuzzerVerifier into a unit test.
3) Move the comment from FuzzerRunner class to ExpressionFuzzerVerifier since it describes the later.


Next diff :
4) Move all the flags from ExpressionFuzzerVerifier to FuzzerRunner and pass them through ExpressionFuzzerVerifier::Options .

1. spark fuzzer used to only support and, or not it uses all of them "and,or,cast,coalesce,if,switch".

Differential Revision: D51856248

velox/expression/tests/ExpressionFuzzer.cpp

@@ -32,7 +32,6 @@
 namespace facebook::velox::test {
 
 namespace {
-
 using exec::SignatureBinder;
 using exec::SignatureBinderBase;
 
@@ -71,15 +70,286 @@ class FullSignatureBinder : public SignatureBinderBase {
   bool bound_{false};
 };
 
+static const std::vector<std::string> kIntegralTypes{
+    "tinyint",
+    "smallint",
+    "integer",
+    "bigint",
+    "boolean"};
+
+static const std::vector<std::string> kFloatingPointTypes{"real", "double"};
+
+facebook::velox::exec::FunctionSignaturePtr makeCastSignature(
+    const std::string& fromType,
+    const std::string& toType) {
+  return facebook::velox::exec::FunctionSignatureBuilder()
+      .argumentType(fromType)
+      .returnType(toType)
+      .build();
+}
+
+void addCastFromIntegralSignatures(
+    const std::string& toType,
+    std::vector<facebook::velox::exec::FunctionSignaturePtr>& signatures) {
+  for (const auto& fromType : kIntegralTypes) {
+    signatures.push_back(makeCastSignature(fromType, toType));
+  }
+}
+
+void addCastFromFloatingPointSignatures(
+    const std::string& toType,
+    std::vector<facebook::velox::exec::FunctionSignaturePtr>& signatures) {
+  for (const auto& fromType : kFloatingPointTypes) {
+    signatures.push_back(makeCastSignature(fromType, toType));
+  }
+}
+
+void addCastFromVarcharSignature(
+    const std::string& toType,
+    std::vector<facebook::velox::exec::FunctionSignaturePtr>& signatures) {
+  signatures.push_back(makeCastSignature("varchar", toType));
+}
+
+void addCastFromTimestampSignature(
+    const std::string& toType,
+    std::vector<facebook::velox::exec::FunctionSignaturePtr>& signatures) {
+  signatures.push_back(makeCastSignature("timestamp", toType));
+}
+
+void addCastFromDateSignature(
+    const std::string& toType,
+    std::vector<facebook::velox::exec::FunctionSignaturePtr>& signatures) {
+  signatures.push_back(makeCastSignature("date", toType));
+}
+
+std::vector<facebook::velox::exec::FunctionSignaturePtr>
+getSignaturesForCast() {
+  std::vector<facebook::velox::exec::FunctionSignaturePtr> signatures;
+
+  // To integral types.
+  for (const auto& toType : kIntegralTypes) {
+    addCastFromIntegralSignatures(toType, signatures);
+    addCastFromFloatingPointSignatures(toType, signatures);
+    addCastFromVarcharSignature(toType, signatures);
+  }
+
+  // To floating-point types.
+  for (const auto& toType : kFloatingPointTypes) {
+    addCastFromIntegralSignatures(toType, signatures);
+    addCastFromFloatingPointSignatures(toType, signatures);
+    addCastFromVarcharSignature(toType, signatures);
+  }
+
+  // To varchar type.
+  addCastFromIntegralSignatures("varchar", signatures);
+  addCastFromFloatingPointSignatures("varchar", signatures);
+  addCastFromVarcharSignature("varchar", signatures);
+  addCastFromDateSignature("varchar", signatures);
+  addCastFromTimestampSignature("varchar", signatures);
+
+  // To timestamp type.
+  addCastFromVarcharSignature("timestamp", signatures);
+  addCastFromDateSignature("timestamp", signatures);
+
+  // To date type.
+  addCastFromVarcharSignature("date", signatures);
+  addCastFromTimestampSignature("date", signatures);
+
+  // For each supported translation pair T --> U, add signatures of array(T) -->
+  // array(U), map(varchar, T) --> map(varchar, U), row(T) --> row(U).
+  auto size = signatures.size();
+  for (auto i = 0; i < size; ++i) {
+    auto from = signatures[i]->argumentTypes()[0].baseName();
+    auto to = signatures[i]->returnType().baseName();
+
+    signatures.push_back(makeCastSignature(
+        fmt::format("array({})", from), fmt::format("array({})", to)));
+
+    signatures.push_back(makeCastSignature(
+        fmt::format("map(varchar, {})", from),
+        fmt::format("map(varchar, {})", to)));
+
+    signatures.push_back(makeCastSignature(
+        fmt::format("row({})", from), fmt::format("row({})", to)));
+  }
+  return signatures;
+}
+
+static const std::unordered_map<
+    std::string,
+    std::vector<facebook::velox::exec::FunctionSignaturePtr>>
+    kSpecialForms = {
+        {"and",
+         std::vector<facebook::velox::exec::FunctionSignaturePtr>{
+             // Signature: and (condition,...) -> output:
+             // boolean, boolean,.. -> boolean
+             facebook::velox::exec::FunctionSignatureBuilder()
+                 .argumentType("boolean")
+                 .argumentType("boolean")
+                 .variableArity()
+                 .returnType("boolean")
+                 .build()}},
+        {"or",
+         std::vector<facebook::velox::exec::FunctionSignaturePtr>{
+             // Signature: or (condition,...) -> output:
+             // boolean, boolean,.. -> boolean
+             facebook::velox::exec::FunctionSignatureBuilder()
+                 .argumentType("boolean")
+                 .argumentType("boolean")
+                 .variableArity()
+                 .returnType("boolean")
+                 .build()}},
+        {"coalesce",
+         std::vector<facebook::velox::exec::FunctionSignaturePtr>{
+             // Signature: coalesce (input,...) -> output:
+             // T, T,.. -> T
+             facebook::velox::exec::FunctionSignatureBuilder()
+                 .typeVariable("T")
+                 .argumentType("T")
+                 .argumentType("T")
+                 .variableArity()
+                 .returnType("T")
+                 .build()}},
+        {
+            "if",
+            std::vector<facebook::velox::exec::FunctionSignaturePtr>{
+                // Signature: if (condition, then) -> output:
+                // boolean, T -> T
+                facebook::velox::exec::FunctionSignatureBuilder()
+                    .typeVariable("T")
+                    .argumentType("boolean")
+                    .argumentType("T")
+                    .returnType("T")
+                    .build(),
+                // Signature: if (condition, then, else) -> output:
+                // boolean, T, T -> T
+                facebook::velox::exec::FunctionSignatureBuilder()
+                    .typeVariable("T")
+                    .argumentType("boolean")
+                    .argumentType("T")
+                    .argumentType("T")
+                    .returnType("T")
+                    .build()},
+        },
+        {
+            "switch",
+            std::vector<facebook::velox::exec::FunctionSignaturePtr>{
+                // Signature: Switch (condition, then) -> output:
+                // boolean, T -> T
+                // This is only used to bind to a randomly selected type for the
+                // output, then while generating arguments, an override is used
+                // to generate inputs that can create variation of multiple
+                // cases and may or may not include a final else clause.
+                facebook::velox::exec::FunctionSignatureBuilder()
+                    .typeVariable("T")
+                    .argumentType("boolean")
+                    .argumentType("T")
+                    .returnType("T")
+                    .build()},
+        },
+        {
+            "cast",
+            /// TODO: Add supported Cast signatures to CastTypedExpr and expose
+            /// them to fuzzer instead of hard-coding signatures here.
+            getSignaturesForCast(),
+        },
+};
+
+static std::unordered_set<std::string> splitNames(const std::string& names) {
+  // Parse, lower case and trim it.
+  std::vector<folly::StringPiece> nameList;
+  folly::split(',', names, nameList);
+  std::unordered_set<std::string> nameSet;
+
+  for (const auto& it : nameList) {
+    auto str = folly::trimWhitespace(it).toString();
+    folly::toLowerAscii(str);
+    nameSet.insert(str);
+  }
+  return nameSet;
+}
+
+static std::pair<std::string, std::string> splitSignature(
+    const std::string& signature) {
+  const auto parenPos = signature.find("(");
+
+  if (parenPos != std::string::npos) {
+    return {signature.substr(0, parenPos), signature.substr(parenPos)};
+  }
+
+  return {signature, ""};
+}
+
+// Parse the comma separated list of function names, and use it to filter the
+// input signatures.
+static void filterSignatures(
+    facebook::velox::FunctionSignatureMap& input,
+    const std::string& onlyFunctions,
+    const std::unordered_set<std::string>& skipFunctions) {
+  if (!onlyFunctions.empty()) {
+    // Parse, lower case and trim it.
+    auto nameSet = splitNames(onlyFunctions);
+
+    // Use the generated set to filter the input signatures.
+    for (auto it = input.begin(); it != input.end();) {
+      if (!nameSet.count(it->first)) {
+        it = input.erase(it);
+      } else
+        it++;
+    }
+  }
+
+  for (auto skip : skipFunctions) {
+    // 'skip' can be function name or signature.
+    const auto [skipName, skipSignature] = splitSignature(skip);
+
+    if (skipSignature.empty()) {
+      input.erase(skipName);
+    } else {
+      auto it = input.find(skipName);
+      if (it != input.end()) {
+        // Compiler refuses to reference 'skipSignature' from the lambda as
+        // is.
+        const auto& signatureToRemove = skipSignature;
+
+        auto removeIt = std::find_if(
+            it->second.begin(), it->second.end(), [&](const auto& signature) {
+              return signature->toString() == signatureToRemove;
+            });
+        VELOX_CHECK(
+            removeIt != it->second.end(), "Skip signature not found: {}", skip);
+        it->second.erase(removeIt);
+      }
+    }
+  }
+}
+
+static void appendSpecialForms(
+    facebook::velox::FunctionSignatureMap& signatureMap,
+    const std::string& specialForms) {
+  auto specialFormNames = splitNames(specialForms);
+  for (const auto& [name, signatures] : kSpecialForms) {
+    if (specialFormNames.count(name) == 0) {
+      LOG(INFO) << "Skipping special form: " << name;
+      continue;
+    }
+    std::vector<const facebook::velox::exec::FunctionSignature*> rawSignatures;
+    for (const auto& signature : signatures) {
+      rawSignatures.push_back(signature.get());
+    }
+    signatureMap.insert({name, std::move(rawSignatures)});
+  }
+}
+
 /// Returns if `functionName` with the given `argTypes` is deterministic.
 /// Returns true if the function was not found or determinism cannot be
 /// established.
 bool isDeterministic(
     const std::string& functionName,
     const std::vector<TypePtr>& argTypes) {
   // We know that the 'cast', 'and', and 'or' special forms are deterministic.
-  // Hard-code them here because they are not real functions and hence cannot be
-  // resolved by the code below.
+  // Hard-code them here because they are not real functions and hence cannot
+  // be resolved by the code below.
   if (functionName == "and" || functionName == "or" ||
       functionName == "coalesce" || functionName == "if" ||
       functionName == "switch" || functionName == "cast") {
@@ -93,9 +363,9 @@ bool isDeterministic(
   }
 
   // Vector functions are a bit more complicated. We need to fetch the list of
-  // available signatures and check if any of them bind given the current input
-  // arg types. If it binds (if there's a match), we fetch the function and
-  // return the isDeterministic bool.
+  // available signatures and check if any of them bind given the current
+  // input arg types. If it binds (if there's a match), we fetch the function
+  // and return the isDeterministic bool.
   try {
     if (auto vectorFunctionSignatures =
             exec::getVectorFunctionSignatures(functionName)) {
@@ -110,12 +380,12 @@ bool isDeterministic(
       }
     }
   }
-  // TODO: Some stateful functions can only be built when constant arguments are
-  // passed, making the getVectorFunction() call above to throw. We only have a
-  // few of these functions, so for now we assume they are deterministic so they
-  // are picked for Fuzz testing. Once we make the isDeterministic() flag static
-  // (and hence we won't need to build the function object in here) we can clean
-  // up this code.
+  // TODO: Some stateful functions can only be built when constant arguments
+  // are passed, making the getVectorFunction() call above to throw. We only
+  // have a few of these functions, so for now we assume they are
+  // deterministic so they are picked for Fuzz testing. Once we make the
+  // isDeterministic() flag static (and hence we won't need to build the
+  // function object in here) we can clean up this code.
   catch (const std::exception& e) {
     LOG(WARNING) << "Unable to determine if '" << functionName
                  << "' is deterministic or not. Assuming it is.";
@@ -178,8 +448,8 @@ bool containTypeName(
   return false;
 }
 
-// Determine whether the signature has an argument or return type that contains
-// typeName. typeName should be in lower case.
+// Determine whether the signature has an argument or return type that
+// contains typeName. typeName should be in lower case.
 bool useTypeName(
     const exec::FunctionSignature& signature,
     const std::string& typeName) {
@@ -237,7 +507,8 @@ BufferPtr extractNonNullIndices(const RowVectorPtr& data) {
 }
 
 /// Wraps child vectors of the specified 'rowVector' in dictionary using
-/// specified 'indices'. Returns new RowVector created from the wrapped vectors.
+/// specified 'indices'. Returns new RowVector created from the wrapped
+/// vectors.
 RowVectorPtr wrapChildren(
     const BufferPtr& indices,
     const RowVectorPtr& rowVector) {
@@ -283,7 +554,7 @@ uint32_t levelOfNesting(const TypePtr& type) {
 } // namespace
 
 ExpressionFuzzer::ExpressionFuzzer(
-    const FunctionSignatureMap& signatureMap,
+    FunctionSignatureMap signatureMap,
     size_t initialSeed,
     const std::shared_ptr<VectorFuzzer>& vectorFuzzer,
     const std::optional<ExpressionFuzzer::Options>& options)
@@ -293,6 +564,10 @@ ExpressionFuzzer::ExpressionFuzzer(
   VELOX_CHECK(vectorFuzzer, "Vector fuzzer must be provided");
   seed(initialSeed);
 
+  appendSpecialForms(signatureMap, options_.specialForms);
+  filterSignatures(
+      signatureMap, options_.useOnlyFunctions, options_.skipFunctions);
+
   size_t totalFunctions = 0;
   size_t totalFunctionSignatures = 0;
   size_t supportedFunctionSignatures = 0;