Add error handling framework

Change-Id: I79e914a63fe0834e165c799bc39065613ea5d729
Signed-off-by: Gabor Hosszu <[email protected]>

Author: gaborh-da

core/errors/errors.go

@@ -0,0 +1,180 @@
+/*
+ Copyright Digital Asset Holdings, LLC 2016 All Rights Reserved.
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+*/
+
+package errors
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"runtime"
+)
+
+// MaxCallStackLength is the maximum length of the stored call stack
+const MaxCallStackLength = 30
+
+// ComponentCode shows the originating component/module
+type ComponentCode uint
+
+// ReasonCode for low level error description
+type ReasonCode uint
+
+// Return codes
+const (
+	Utility ComponentCode = iota
+)
+
+// Result codes
+const (
+	// Placeholder
+	UnknownError ReasonCode = iota
+)
+
+// CallStackError is a general interface for
+// Fabric errors
+type CallStackError interface {
+	error
+	GetStack() string
+	GetErrorCode() string
+	GetComponentCode() ComponentCode
+	GetReasonCode() ReasonCode
+}
+
+type errormap map[string]map[string]map[string]string
+
+var emap errormap
+
+const language string = "en"
+
+func init() {
+	initErrors()
+}
+
+func initErrors() {
+	e := json.Unmarshal([]byte(errorCodes), &emap)
+	if e != nil {
+		panic(e)
+	}
+}
+
+type callstack []uintptr
+
+// the main idea is to have an error package
+// HLError is the 'super class' of all errors
+// It has a predefined, general error message
+// One has to create his own error in order to
+// create something more useful
+type hlError struct {
+	stack         callstack
+	componentcode ComponentCode
+	reasoncode    ReasonCode
+	stackGetter   func(callstack) string
+}
+
+// newHLError creates a general HL error with a predefined message
+// and a stacktrace.
+func newHLError(debug bool) *hlError {
+	e := &hlError{}
+	setupHLError(e, debug)
+	return e
+}
+
+func setupHLError(e *hlError, debug bool) {
+	e.componentcode = Utility
+	e.reasoncode = UnknownError
+	if !debug {
+		e.stackGetter = noopGetStack
+		return
+	}
+	e.stackGetter = getStack
+	stack := make([]uintptr, MaxCallStackLength)
+	skipCallersAndSetupHL := 2
+	length := runtime.Callers(skipCallersAndSetupHL, stack[:])
+	e.stack = stack[:length]
+}
+
+// Error comes from the error interface
+func (h *hlError) Error() string {
+	return h.componentcode.Message(h.reasoncode)
+}
+
+// GetStack returns the call stack as a string
+func (h *hlError) GetStack() string {
+	return h.stackGetter(h.stack)
+}
+
+// GetComponentCode returns the Return code
+func (h *hlError) GetComponentCode() ComponentCode {
+	return h.componentcode
+}
+
+// GetReasonCode returns the Reason code
+func (h *hlError) GetReasonCode() ReasonCode {
+	return h.reasoncode
+}
+
+// GetErrorCode returns a formatted error code string
+func (h *hlError) GetErrorCode() string {
+	return fmt.Sprintf("%d-%d", h.componentcode, h.reasoncode)
+}
+
+// Message returns the corresponding error message for this code in default language
+func (c ComponentCode) Message(reasoncode ReasonCode) string {
+	return emap[fmt.Sprintf("%d", c)][fmt.Sprintf("%d", reasoncode)][language]
+}
+
+// MessageIn returns the corresponding error message for this code in 'language'
+func (c ComponentCode) MessageIn(reasoncode ReasonCode, language string) string {
+	return emap[fmt.Sprintf("%d", c)][fmt.Sprintf("%d", reasoncode)][language]
+}
+
+// Error creates a CallStackError using a specific Component Code and
+// Reason Code (no callstack is recorded)
+func Error(componentcode ComponentCode, reasoncode ReasonCode) CallStackError {
+	return newCustomError(componentcode, reasoncode, false)
+}
+
+// ErrorWithCallstack creates a CallStackError using a specific Component Code and
+// Reason Code and fills its callstack
+func ErrorWithCallstack(componentcode ComponentCode, reasoncode ReasonCode) CallStackError {
+	return newCustomError(componentcode, reasoncode, true)
+}
+
+func newCustomError(componentcode ComponentCode, reasoncode ReasonCode, generateStack bool) CallStackError {
+	e := &hlError{}
+	setupHLError(e, generateStack)
+	e.componentcode = componentcode
+	e.reasoncode = reasoncode
+	return e
+}
+
+func getStack(stack callstack) string {
+	buf := bytes.Buffer{}
+	if stack == nil {
+		return fmt.Sprintf("No call stack available")
+	}
+	for _, pc := range stack {
+		f := runtime.FuncForPC(pc)
+		file, line := f.FileLine(pc)
+		buf.WriteString(fmt.Sprintf("%s:%d %s\n", file, line, f.Name()))
+	}
+
+	return fmt.Sprintf("%s", buf.Bytes())
+}
+
+func noopGetStack(stack callstack) string {
+	return ""
+}

core/errors/errors_json.go

@@ -0,0 +1,24 @@
+/*
+ Copyright Digital Asset Holdings, LLC 2016 All Rights Reserved.
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+*/
+
+package errors
+
+const errorCodes string = `
+{"0" :
+    {"0" :
+        {"en": "An unknown error occured."}
+    }
+}`

core/errors/errors_test.go

@@ -0,0 +1,61 @@
+/*
+ Copyright Digital Asset Holdings, LLC 2016 All Rights Reserved.
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+*/
+
+package errors
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestError(t *testing.T) {
+	e := Error(Utility, UnknownError)
+	s := e.GetStack()
+	if s != "" {
+		t.Fatalf("No error stack should have been recorded.")
+	}
+}
+
+func TestErrorWithCallstack(t *testing.T) {
+	e := ErrorWithCallstack(Utility, UnknownError)
+	s := e.GetStack()
+	if s == "" {
+		t.Fatalf("No error stack was recorded.")
+	}
+}
+
+func oops() CallStackError {
+	return Error(Utility, UnknownError)
+}
+
+func ExampleError() {
+	err := oops()
+	if err != nil {
+		fmt.Printf("%s\n", err.Error())
+		fmt.Printf("%s\n", err.GetErrorCode())
+		fmt.Printf("%d\n", err.GetComponentCode())
+		fmt.Printf("%d\n", err.GetReasonCode())
+		fmt.Printf("%s\n", err.GetComponentCode().Message(err.GetReasonCode()))
+		fmt.Printf("%s", err.GetComponentCode().MessageIn(err.GetReasonCode(), "en"))
+		// Output:
+		// An unknown error occured.
+		// 0-0
+		// 0
+		// 0
+		// An unknown error occured.
+		// An unknown error occured.
+	}
+}