LogDog: Add collector service implementation.

server/internal/logdog/config/fileConfig.go

+// Copyright 2016 The Chromium Authors. All rights reserved.

[iannucci, 2016/02/05 23:41:01]

I feel like this sort of thing should really be somewhere in common/config. It's
not related to logdog at all, is it?

[dnj (Google), 2016/02/06 04:10:37]

If it were fully implemented I'd agree, but ATM it's a very specific partial
implementation based on what this package uses.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package config
+
+import (
+        "bytes"
+        "crypto/sha256"
+        "encoding/hex"
+        "errors"
+        "net/url"
+        "os"
+
+        "github.com/luci/luci-go/common/config"
+)
+
+var errNotImplemented = errors.New("not implemented")
+
+// fileConfig is an implementation of config.Interface that represents itself
+// as a configuration instance with one specific ConfigSet containing one
+// specific file.
+//
+// This is a partial implementation of the config.Interface interface sufficient
+// for a ConfigManager to use.
+type fileConfig struct {
+        path string
+
+        configSet  string
+        configPath string
+}
+
+var _ config.Interface = (*fileConfig)(nil)
+
+func (fc *fileConfig) GetConfig(configSet, path string, hashOnly bool) (*config.Config, error) {
+        if configSet != fc.configSet || path != fc.configPath {
+                return nil, config.ErrNoConfig
+        }
+
+        buf := bytes.Buffer{}
+        fd, err := os.Open(fc.path)
+        if err != nil {
+                return nil, err
+        }
+        defer fd.Close()
+
+        _, err = buf.ReadFrom(fd)
+        if err != nil {
+                return nil, err
+        }
+
+        hash := sha256.Sum256(buf.Bytes())
+        return &config.Config{
+                Content:     buf.String(),
+                ContentHash: hex.EncodeToString(hash[:]),
+        }, nil
+}
+
+func (fc *fileConfig) GetConfigByHash(contentHash string) (string, error) {
+        return "", errNotImplemented
+}
+
+func (fc *fileConfig) GetConfigSetLocation(configSet string) (*url.URL, error) {
+        return nil, errNotImplemented
+}
+
+func (fc *fileConfig) GetProjectConfigs(path string, hashesOnly bool) ([]config.Config, error) {
+        return nil, errNotImplemented
+}
+
+func (fc *fileConfig) GetProjects() ([]config.Project, error) {
+        return nil, errNotImplemented
+}
+
+func (fc *fileConfig) GetRefConfigs(path string, hashesOnly bool) ([]config.Config, error) {
+        return nil, errNotImplemented
+}
+
+func (fc *fileConfig) GetRefs(projectID string) ([]string, error) {
+        return nil, errNotImplemented
+}