golden/pdfxform a pdf rasterization server

golden/go/pdfxform/main.go

+// pdfxform is a server that rasterizes PDF documents into PNG
+package main
+
+import (
+        "bytes"
+        "crypto/md5"
+        "encoding/hex"
+        "encoding/json"
+        "flag"
+        "fmt"
+        "io"
+        "io/ioutil"
+        "net/http"
+        "os"
+        "os/user"
+        "path"
+        "path/filepath"
+        "runtime"
+        "strings"
+        "time"
+
+        "github.com/skia-dev/glog"
+        "go.skia.org/infra/go/auth"
+        "go.skia.org/infra/go/gs"
+        "go.skia.org/infra/go/pdf"
+        "go.skia.org/infra/go/util"
+        "go.skia.org/infra/perf/go/goldingester"
+        "google.golang.org/api/storage/v1"
+)
+
+////////////////////////////////////////////////////////////////////////////////
+
+const (
+        pngExt = "png"

[jcgregorio, 2015/06/26 19:21:05]

PNG_EXT

[hal.canary, 2015/06/26 22:10:52]

Done.

+        pdfExt = "pdf"

[jcgregorio, 2015/06/26 19:21:06]

PDF_EXT

[hal.canary, 2015/06/26 22:10:52]

Done.

+)
+
+////////////////////////////////////////////////////////////////////////////////
+
+// md5OfFile calculates the MD5 checksum of a file.
+func md5OfFile(path string) (string, error) {
+        md5 := md5.New()
+        f, err := os.Open(path)
+        if err != nil {
+                return "", err
+        }
+        defer util.Close(f)
+        if _, err = io.Copy(md5, f); err != nil {
+                return "", err
+        }
+        return hex.EncodeToString(md5.Sum(nil)), nil
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+// removeIf is like util.Remove, but logs no error if the file does not exist.
+func removeIf(path string) {
+        if err := os.Remove(path); err != nil {
+                if !os.IsNotExist(err) {
+                        glog.Errorf("Failed to Remove(%s): %v", path, err)
+                }
+        }
+}
+
+// isPDF returns true if the path appears to point to a PDF file.
+func isPDF(path string) bool {
+        f, err := os.Open(path)
+        if err != nil {
+                return false
+        }
+        defer util.Close(f)
+        var buffer [4]byte
+        if n, err := f.Read(buffer[:]); n != 4 || err != nil {
+                return false
+        }
+        var magic = [4]byte{'%', 'P', 'D', 'F'}
+        return bytes.Equal(magic[:], buffer[:])
+}
+
+// writeTo opens a file and dumps the contents of the reader into it.
+func writeTo(path string, reader *io.ReadCloser) error {
+        defer util.Close(*reader)
+        file, err := os.Create(path)
+        if err == nil {
+                _, err = io.Copy(file, *reader)
+        }
+        return err
+}
+
+// assertNil logs the err and exits if it is not nil.
+func assertNil(err error) {
+        if err != nil {
+                errMsg := ""
+                if _, fileName, line, ok := runtime.Caller(1); ok {
+                        errMsg = fmt.Sprintf("-called from: %s:%d", fileName, line)
+                }
+                glog.Fatalf("Unexpected error %s: %s", errMsg, err)
+        }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+// storageClient struct is used for uploading to cloud storage
+type storageClient struct {
+        httpClient     *http.Client
+        storageService *storage.Service
+}
+
+// getClient returns an authorized storage.Service and the
+// corresponding http.Client; if anything goes wrong, it logs a fatal
+// error.
+func getClient(cacheFilePath string) storageClient {
+        config := auth.OAuthConfig(cacheFilePath, auth.SCOPE_FULL_CONTROL)

[jcgregorio, 2015/06/26 19:21:05]

Create two command line flags:

  --local
  --oauth_cache_file

ala

   local = flag.Bool("local", false, "True if not running in prod.")
   oauthCacheFile = flag.String("oauth_cache_file", "oauth_cache.dat",
"..description..")


Then call:

	if client, err = auth.NewClient(!*local, *oauthCacheFile,
auth.SCOPE_FULL_CONTROL, auth.SCOPE_GCE); err != nil {
		glog.Fatalf("Failed to create authenticated HTTP client: %s", err)
	}

[hal.canary, 2015/06/26 22:38:24]

Mostly done.

+        client, err := auth.RunFlow(config)
+        assertNil(err)
+        gsService, err := storage.New(client)
+        assertNil(err)
+        return storageClient{httpClient: client, storageService: gsService}
+}
+
+// gsFetch fetch the object's data from google storage
+func gsFetch(object *storage.Object, sc storageClient) (io.ReadCloser, int64, error) {
+        request, err := gs.RequestForStorageURL(object.MediaLink)
+        if err != nil {
+                return nil, -1, err
+        }
+        resp, err := sc.httpClient.Do(request)
+        if err != nil {
+                return nil, -1, err
+        }
+        if resp.StatusCode != 200 {
+                resp.Body.Close()
+                return nil, -1, fmt.Errorf("Failed to retrieve: %s %d %s", object.MediaLink, resp.StatusCode, resp.Status)
+        }
+        return resp.Body, resp.ContentLength, nil
+}
+
+// uploadFile uploads the specified file to the remote dir in Google
+// Storage. It also sets the appropriate ACLs on the uploaded file.
+// If the file already exists on the server, do nothing.
+func uploadFile(sc storageClient, input io.Reader, storageBucket, storagePath, accessControlEntity string) (bool, error) {
+        obj, _ := sc.storageService.Objects.Get(storageBucket, storagePath).Do()
+        if obj != nil {
+                return false, nil // noclobber
+        }
+        fullPath := fmt.Sprintf("gs://%s/%s", storageBucket, storagePath)
+        object := &storage.Object{Name: storagePath}
+        if _, err := sc.storageService.Objects.Insert(storageBucket, object).Media(input).Do(); err != nil {
+                return false, fmt.Errorf("Objects.Insert(%s) failed: %s", fullPath, err)
+        }
+        objectAcl := &storage.ObjectAccessControl{
+                Bucket: storageBucket, Entity: accessControlEntity, Object: storagePath, Role: "READER",
+        }
+        if _, err := sc.storageService.ObjectAccessControls.Insert(storageBucket, storagePath, objectAcl).Do(); err != nil {
+                return false, fmt.Errorf("Could not update ACL of %s: %s", fullPath, err)
+        }
+        return true, nil
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+// The pdfXformer struct holds state (results, counter) and constants (bucket, directories)
+type pdfXformer struct {
+        client                 storageClient
+        storageBucket          string
+        storageJsonDirectory   string
+        storageImagesDirectory string
+        accessControlEntity    string
+        rasterizers            []pdf.Rasterizer
+        results                map[string]map[int]string
+        counter                int
+        identifier             string
+}
+
+const errorImageMd5 = "45aa8af265d16839402583df5756a7c6"
+
+// rasterizeOnce applies a single rastetizer to the given pdf file.
+// If the rasterizer fails, use the errorImage.  If everything
+// succeeds, upload the PNG.
+func (xformer *pdfXformer) rasterizeOnce(pdfPath string, rasterizerIndex int) (string, error) {
+        rasterizer := xformer.rasterizers[rasterizerIndex]
+        tempdir := filepath.Dir(pdfPath)
+        pngPath := path.Join(tempdir, fmt.Sprintf("%s.%s", rasterizer.String(), pngExt))
+        defer removeIf(pngPath)

[stephana, 2015/06/26 20:02:59]

We have a function for this already.

defer util.Remove(pngPath)

should do the trick and then you can get rid the removeIf function. 

[hal.canary, 2015/06/26 22:10:52]

I modified the name of the function to make it clear how it differs.

+        glog.Infof("> > > > rasterizing with %s", rasterizer)
+        err := rasterizer.Rasterize(pdfPath, pngPath)
+        if err != nil {
+                glog.Warningf("rasterizing %s with %s failed: %s", filepath.Base(pdfPath), rasterizer.String(), err)
+                return errorImageMd5, nil
+        }
+        md5, err := md5OfFile(pngPath)
+        if err != nil {
+                return "", err
+        }
+        f, err := os.Open(pngPath)
+        if err != nil {
+                return "", err
+        }
+        defer util.Close(f)
+        pngUploadPath := fmt.Sprintf("%s/%s.%s", xformer.storageImagesDirectory, md5, pngExt)
+        didUpload, err := uploadFile(xformer.client, f, xformer.storageBucket, pngUploadPath, xformer.accessControlEntity)
+        if err != nil {
+                return "", err
+        }
+        if didUpload {
+                glog.Infof("> > > > uploaded %s", pngUploadPath)
+        }
+        return md5, nil
+}
+
+// makeTmpDir returns a nicely-named directory for temp files in $TMPDIR
+func (xformer *pdfXformer) makeTmpDir() string {
+        if xformer.identifier == "" {
+                var host, userName string
+                if h, err := os.Hostname(); err == nil {
+                        host = h
+                        if i := strings.Index(host, "."); i >= 0 {
+                                host = host[:i]
+                        }
+                }
+                if currentUser, err := user.Current(); err == nil {
+                        userName = currentUser.Username
+                }
+                userName = strings.Replace(userName, `\`, "_", -1)
+                xformer.identifier = fmt.Sprintf("%s.%s.%s.tmp.%d.", filepath.Base(os.Args[0]), host, userName, os.Getpid())

[jcgregorio, 2015/06/26 19:21:06]

When this is run in prod the exe will sit in /usr/local/bin, so you can't use
the exe directory to store data.

Add a command line flag:

   --data_dir

ala

   dataDir = flag.String("data_dir", "", "Directory to store data in.")

Use *dataDir as the place to store the data, if *dataDir is not set then you can
use ioutil.TempDir().

[hal.canary, 2015/06/26 22:10:52]

Done.

+        }
+        tempdir, err := ioutil.TempDir("", xformer.identifier)
+        assertNil(err)
+        return tempdir
+}
+
+func newResult(key map[string]string, rasterizerName, digest string) goldingester.Result {
+        keyCopy := map[string]string{}
+        for k, v := range key {
+                keyCopy[k] = v
+        }
+        keyCopy["rasterizer"] = rasterizerName
+        options := map[string]string{"ext": pngExt}
+        return goldingester.Result{Key: keyCopy, Digest: digest, Options: options}
+}
+
+// processResult rasterizes a single PDF result and returns a set of new results.
+func (xformer *pdfXformer) processResult(res goldingester.Result) []goldingester.Result {
+        rasterizedResults := []goldingester.Result{}
+        resultMap, found := xformer.results[res.Digest]
+        if found {
+                // Skip rasterizion steps: big win.
+                for index, rasterizer := range xformer.rasterizers {
+                        digest, ok := resultMap[index]
+                        if ok {
+                                rasterizedResults = append(rasterizedResults,
+                                        newResult(res.Key, rasterizer.String(), digest))
+                        } else {
+                                glog.Errorf("missing rasterizer %s on %s", rasterizer.String(), res.Digest)
+                        }
+                }
+                return rasterizedResults
+        }
+
+        tempdir := xformer.makeTmpDir()
+        defer util.RemoveAll(tempdir)
+        pdfPath := path.Join(tempdir, fmt.Sprintf("%s.pdf", res.Digest))
+        objectName := fmt.Sprintf("%s/%s.pdf", xformer.storageImagesDirectory, res.Digest)
+        storageURL := fmt.Sprintf("gs://%s/%s", xformer.storageBucket, objectName)
+        object, err := xformer.client.storageService.Objects.Get(xformer.storageBucket, objectName).Do()
+        if err != nil {
+                glog.Errorf("unable to find %s: %s", storageURL, err)
+                return []goldingester.Result{}
+        }
+        pdfData, _, err := gsFetch(object, xformer.client)
+        if err != nil {
+                glog.Errorf("unable to retrieve %s: %s", storageURL, err)
+                return []goldingester.Result{}
+        }
+        writeTo(pdfPath, &pdfData)
+        if !isPDF(pdfPath) {
+                glog.Errorf("%s is not a PDF", objectName)
+                return []goldingester.Result{}
+        }
+        resultMap = map[int]string{}
+        for index, rasterizer := range xformer.rasterizers {
+                digest, err := xformer.rasterizeOnce(pdfPath, index)
+                if err != nil {
+                        glog.Errorf("rasterizer %s failed on %s.pdf: %s", rasterizer, res.Digest, err)
+                        continue
+                }
+                rasterizedResults = append(rasterizedResults,
+                        newResult(res.Key, rasterizer.String(), digest))
+                resultMap[index] = digest
+        }
+        xformer.results[res.Digest] = resultMap
+        return rasterizedResults
+}
+
+// processJsonFile reads a json file and produces a new json file
+// with rasterized results.
+func (xformer *pdfXformer) processJsonFile(jsonFileObject *storage.Object) {
+        jsonURL := fmt.Sprintf("gs://%s/%s", xformer.storageBucket, jsonFileObject.Name)
+        if jsonFileObject.Metadata["rasterized"] == "true" {
+                glog.Infof("> > skipping %s (already processed) {%d}", jsonURL, xformer.counter)
+                return
+        }
+        body, length, err := gsFetch(jsonFileObject, xformer.client)
+        if err != nil {
+                glog.Errorf("Failed to fetch %s", jsonURL)
+                return
+        }
+        if 0 == length {
+                util.Close(body)
+                glog.Infof("> > skipping %s (empty file) {%d}", jsonURL, xformer.counter)
+                return
+        }
+        dmstruct := goldingester.DMResults{}
+        err = json.NewDecoder(body).Decode(&dmstruct)
+        util.Close(body)
+        if err != nil {
+                glog.Errorf("Failed to parse %s", jsonURL)
+                return
+        }
+        countPdfResults := 0
+        for _, res := range dmstruct.Results {
+                if res.Options["ext"] == pdfExt {
+                        countPdfResults++
+                }
+        }
+        if 0 == countPdfResults {
+                glog.Infof("> > 0 PDFs found %s {%d}", jsonURL, xformer.counter)
+                xformer.setRasterized(jsonFileObject)
+                return
+        }
+
+        glog.Infof("> > processing %d pdfs of %d results {%d}", countPdfResults, len(dmstruct.Results), xformer.counter)
+        rasterizedResults := []*goldingester.Result{}
+        i := 0
+        for _, res := range dmstruct.Results {
+                if res.Options["ext"] == pdfExt {
+                        i++
+                        glog.Infof("> > > processing %s.pdf [%d/%d] {%d}", res.Digest, i, countPdfResults, xformer.counter)
+                        for _, rasterizedResult := range xformer.processResult(*res) {
+                                rasterizedResults = append(rasterizedResults, &rasterizedResult)
+                        }
+                }
+        }
+        newDMStruct := goldingester.DMResults{
+                BuildNumber: dmstruct.BuildNumber,
+                GitHash:     dmstruct.GitHash,
+                Key:         dmstruct.Key,
+                Results:     rasterizedResults,
+        }
+        newJson, err := json.Marshal(newDMStruct)
+        assertNil(err)
+
+        now := time.Now()
+        // Change the date; leave most of the rest of the path components.
+        jsonPathComponents := strings.Split(jsonFileObject.Name, "/") // []string
+        if len(jsonPathComponents) < 4 {
+                fmt.Errorf("unexpected number of path components %q", jsonPathComponents)
+                return
+        }
+        jsonPathComponents = jsonPathComponents[len(jsonPathComponents)-4:]
+        jsonPathComponents[1] += "-pdfxformer"
+        jsonUploadPath := fmt.Sprintf("%s/%d/%02d/%02d/%02d/%s",
+                xformer.storageJsonDirectory,
+                now.Year(),
+                int(now.Month()),
+                now.Day(),
+                now.Hour(),
+                strings.Join(jsonPathComponents, "/"))
+
+        _, err = uploadFile(xformer.client, bytes.NewReader(newJson), xformer.storageBucket, jsonUploadPath, xformer.accessControlEntity)
+        glog.Infof("> > wrote gs://%s/%s", xformer.storageBucket, jsonUploadPath)
+        newJsonFileObject, err := xformer.client.storageService.Objects.Get(xformer.storageBucket, jsonUploadPath).Do()
+        if err != nil {
+                glog.Errorf("Failed to find %s: %s", jsonUploadPath, err)
+        } else {
+                xformer.setRasterized(newJsonFileObject)
+        }
+        xformer.setRasterized(jsonFileObject)
+}
+
+// setRasterized sets the rasterized metadata flag of the given storage.Object
+func (xformer *pdfXformer) setRasterized(jsonFileObject *storage.Object) {
+        if nil == jsonFileObject.Metadata {
+                jsonFileObject.Metadata = map[string]string{}
+        }
+        jsonFileObject.Metadata["rasterized"] = "true"
+        _, err := xformer.client.storageService.Objects.Patch(xformer.storageBucket, jsonFileObject.Name, jsonFileObject).Do()
+        if err != nil {
+                glog.Errorf("Failed to update metadata of %s: %s", jsonFileObject.Name, err)
+        } else {
+                glog.Infof("> > Updated metadata of %s", jsonFileObject.Name)
+        }
+}
+
+// processTimeRange calls gs.GetLatestGSDirs to get a list of
+func (xformer *pdfXformer) processTimeRange(start time.Time, end time.Time) {
+        glog.Infof("Processing time range: (%s, %s)", start.Truncate(time.Second), end.Truncate(time.Second))
+        for _, dir := range gs.GetLatestGSDirs(start.Unix(), end.Unix(), xformer.storageJsonDirectory) {
+                glog.Infof("> Reading gs://%s/%s\n", xformer.storageBucket, dir)
+                requestedObjects := xformer.client.storageService.Objects.List(xformer.storageBucket).Prefix(dir).Fields(
+                        "nextPageToken", "items/updated", "items/md5Hash", "items/mediaLink", "items/name", "items/metadata")
+                for requestedObjects != nil {
+                        responseObjects, err := requestedObjects.Do()
+                        if err != nil {
+                                glog.Errorf("request %#v failed: %s", requestedObjects, err)
+                                continue

[stephana, 2015/06/26 20:02:59]

wouldn't this repeat a failed request indefinitely ?

You could have a counter here and retry for a fixed number of times and then
leave the loop. 

[hal.canary, 2015/06/26 22:10:52]

Done.  Good catch.

+                        }
+                        for _, jsonObject := range responseObjects.Items {
+                                xformer.counter++
+                                glog.Infof("> > Processing object:  gs://%s/%s {%d}", xformer.storageBucket, jsonObject.Name, xformer.counter)
+                                xformer.processJsonFile(jsonObject)
+                        }
+                        if len(responseObjects.NextPageToken) > 0 {
+                                requestedObjects.PageToken(responseObjects.NextPageToken)
+                        } else {
+                                requestedObjects = nil
+                        }
+                }
+        }
+        glog.Infof("finished time range.")
+}
+
+const errorImageData = "\x89PNG\x0D\x0A\x1A\x0A\x00\x00\x00\x0DIHDR\x00\x00" +
+        "\x00\xC1\x00\x00\x00#\x08\x06\x00\x00\x00-\xCEn\x15\x00\x00\x01\xF8IDATx" +
+        "\xDA\xED\x9C\xDB\x8E\xC3 \x0CDK\xB4\xFF\xFF\xCB\xD9\xA7V\x11\x8Ac\x1B\xCC" +
+        "-\x9Cy\xDAf)x\x0C\x03\xB6\x89\x9A\xCE\xF3<?\x00l\x8C\x03\x17\x00D\x00\x00" +
+        "\"\x00\x00\x11\x00\x80\x08\x00@\x04\x00 \x02\x00\x10\x01\x00\x88\x00\x80]" +
+        "\xF1\xB7\x8A\xA1)\xA5O\xCB\xCB\xED\x94\xD2\xEF\xEF\x1E\x97\xE8w|z\xDB\xE0" +
+        "\xF1I\xA9]w\x9CZ\xF2,\xE9\xFBXE\x00o\xC2\x0A|\xDE\xE6\xF3\xA5O\x82^\x93" +
+        "\xD1k\xE7}\xE23\xEBk\\5v\xAD\xF0j\x1A9\x01 '(\x8D\xB5\xA4\xD8\xCB\x13Gjm" +
+        "\xF3\xFF\x7F??\xC5\xD2\xD2\x98\x9A\xFDZ\xECj\xD9\xE5j\xF9h\xF1l\xFE}\xADM" +
+        "\xCE\xCB\xBA3\xB7\xF4{d\x1ER\xC2-\xEC$\x90\x16\x87\xE7\xB9\xB7\x8F([Z\x85" +
+        "XQ|\xA4>$\x1FzyFqo\xC1\xB7v\xFD\x94\x8E]\x9C\x13H\x8A\x97\x9E_\xAB!\xDA)" +
+        "\xF2m\xFBt\xE2x\xFA)\x8DU-\xBB\xB1\x87\xBB\xC6\xC7\xE3w\xEB\x84\xDF\xB5" +
+        "\xD7*mV\xBF[\xE6\xBA\xB6\xAA\xE3\x99\xCB\xAE\"\xB83&\"\x01\xEA\x95D\x95" +
+        "\x8E#M\xD4\x88\xD2\xEDu\xA1J\x0BDj\xBF\xCA<\xD5\xF8dxu\xC8cHT\xCD\xB8u" +
+        "\x15\xC9j\xE7N\xA5\xC5\xDE\xA1\xE5\xF0\xC48\xD2xI\xB1\xD21\xBB\xC2D\xB3" +
+        "\xF87\xA8\x0Ey\x9D\xA2\xC5iZ\xD5\xC4+\x84\x91\xA1\x94\x97\xFB\xDB\x04\x10" +
+        "\xCD\xB7\xF7&x\xF4Z(Z\xFBY/U\xBC\xE1\xDAn\xBF[\xF0\x06\xBEG\xCF\x1D\xE3" +
+        "\xFA\\+\xEF\xD5\x8C\x15\xD5\x7FM\xBE\xD2bW\xCC9\xCE\xB4\x10{\xCE\xA5\xC5'" +
+        "\xD3'\xC6ye\xC3\xBA\xBB\xE49C\x9E[D]\x9EX9YK\xA8Z\x9F\x1E;g\x0B\xB1\"\xC5" +
+        "^:\x97\xB56\x84\x9D\x04R\x89NR\xAD\xB5~\xAF-\x90\x9A{\x80\x11\xDCK\xEF" +
+        "\x06,c\xCC\xC87\"\xB4\xB2\x96\xE4\x8BK\xDF\xFC\xF8\x16\xD8\x1D\xBC@\x07" +
+        "\x10\x01.\x00\x88\x00\x00D\x00\x00\"\x00\x00\x11\x00\x80\x08\x00@\x04\x00" +
+        " \x02\x00\xB6\xC5?\xE4^\x82\xA6\x8A\xB0\x7F'\x00\x00\x00\x00IEND\xAEB`\x82"
+
+// uploadErrorImage should be run once to verify that the image is there

[stephana, 2015/06/26 20:03:00]

This is really not a good idea. The image should not be in here, but a command
line flag. MUCH easier to maintain down the road. And then to a test decode upon
startup. 

[jcgregorio, 2015/06/26 20:08:07]

Upon further thought I agree, should be cmd line flag.

On 2015/06/26 at 20:03:00, stephana wrote:

[hal.canary, 2015/06/26 22:10:52]

Done.

+func (xformer *pdfXformer) uploadErrorImage() {
+        // Check to see that the data is correct.
+        errorImageDataReader := bytes.NewReader([]byte(errorImageData))
+        md5sum := md5.New()
+        _, err := io.Copy(md5sum, errorImageDataReader)
+        assertNil(err)
+        if errorImageMd5 != hex.EncodeToString(md5sum.Sum(nil)) {
+                glog.Fatalf("errorImageData is corrupted")
+        }
+        _, err = errorImageDataReader.Seek(0, 0)
+        assertNil(err)
+
+        errorImagePath := fmt.Sprintf("%s/%s.png", xformer.storageImagesDirectory, errorImageMd5)
+        _, err = uploadFile(xformer.client, errorImageDataReader, xformer.storageBucket, errorImagePath, xformer.accessControlEntity)
+        assertNil(err) // If we can't upload this, we can't upload anything.
+}
+
+// Environment variables: we respect $TMPDIR
+// Arguments: glog uses -logtostderr, -log_dir
+func main() {
+        flag.Parse()

[jcgregorio, 2015/06/26 19:21:06]

Use common.InitWithMetrics.

  https://github.com/google/skia-buildbot/blob/master/go/common/common.go#L38

Also needs a command-line flag added for the graphite server.

+
+        // TODO(halcanary): where should this file exist?
+        configDir := path.Join(os.Getenv("HOME"), ".config")
+        assertNil(os.MkdirAll(configDir, 0700))

[stephana, 2015/06/26 20:03:00]

Making sure that directory exists is already implemented in fileutil:

See: 

https://github.com/google/skia-buildbot/blob/master/golden/go/filediffstore/f...

[hal.canary, 2015/06/26 22:38:24]

Done.

+
+        xformer := pdfXformer{

[stephana, 2015/06/26 20:02:59]

These should not be hard coded, but instead be flags (see skiacorrectness). The
hard coded values can be the defaults for the flag. 

There should also be a flag whether it's run local or not, in the latter case
the oauth info will come from the CGE instance's meta data. 

+                client:                 getClient(path.Join(configDir, "google_storage_token.data")),
+                storageBucket:          "chromium-skia-gm",
+                storageJsonDirectory:   "dm-json-v1",
+                storageImagesDirectory: "dm-images-v1",
+                accessControlEntity:    "domain-google.com",
+                results:                map[string]map[int]string{},
+        }
+
+        xformer.uploadErrorImage()
+
+        for _, rasterizer := range []pdf.Rasterizer{pdf.Pdfium{}, pdf.Poppler{}} {
+                if rasterizer.Enabled() {
+                        xformer.rasterizers = append(xformer.rasterizers, rasterizer)
+                } else {
+                        glog.Infof("rasterizer %s is disabled", rasterizer.String())
+                }
+        }
+        if len(xformer.rasterizers) == 0 {
+                glog.Fatalf("no rasterizers found")
+        }
+
+        end := time.Now()

[stephana, 2015/06/26 20:02:59]

This is not wrong, but the pattern that we use throughout is more like this: 


oneRun := func(start, end int64) {
  ... 
	xformer.processTimeRange(start, end)
  ... 
}

oneRun() 
for _ = range time.Tick(time.Minute) {
   oneRun() 
}

[hal.canary, 2015/06/26 22:10:52]

Done.

+        start := end.Add(-72 * time.Hour)
+        timeTicker := time.Tick(time.Minute)
+        for {
+                xformer.processTimeRange(start, end)
+                glog.Flush() // Flush before waiting for next tick; it may be a while.
+                _ = <-timeTicker
+                start = end
+                end = time.Now()
+        }
+}