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Make file download fail-safe and retry on transient errors #131

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96 changes: 86 additions & 10 deletions src/main/java/io/simplelocalize/cli/client/SimpleLocalizeClient.java
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,8 @@ public class SimpleLocalizeClient
{

private static final String ERROR_MESSAGE_PATH = "$.msg";
private static final int MAX_DOWNLOAD_ATTEMPTS = 3;
private static final long RETRY_DELAY_MILLIS = 1000;
private final HttpClient httpClient;
private final SimpleLocalizeHttpRequestFactory httpRequestFactory;
private final SimpleLocalizeUriFactory uriFactory;
Expand Down Expand Up @@ -129,8 +131,58 @@ public void downloadFile(String url, Path savePath) throws IOException, Interrup
Files.createDirectories(parentDirectory);
}
log.info("Downloading {}", savePath);
HttpResponse<Path> response = httpClient.send(httpRequest, HttpResponse.BodyHandlers.ofFile(savePath, StandardOpenOption.CREATE, StandardOpenOption.WRITE, StandardOpenOption.TRUNCATE_EXISTING));
throwOnError(response);
for (int attempt = 1; ; attempt++)
{
HttpResponse<Path> response;
try
{
response = httpClient.send(httpRequest, HttpResponse.BodyHandlers.ofFile(savePath, StandardOpenOption.CREATE, StandardOpenOption.WRITE, StandardOpenOption.TRUNCATE_EXISTING));
} catch (IOException e)
{
if (attempt >= MAX_DOWNLOAD_ATTEMPTS)
{
throw e;
}
log.warn("Downloading {} failed: {}, retrying ({}/{})", savePath, e.getMessage(), attempt + 1, MAX_DOWNLOAD_ATTEMPTS);
Thread.sleep(RETRY_DELAY_MILLIS * attempt);
continue;
}
if (response.statusCode() == 200)
{
return;
}
// the body handler wrote the error response to savePath; don't leave it there as a translation file
try
{
if (isRetryableStatusCode(response.statusCode()) && attempt < MAX_DOWNLOAD_ATTEMPTS)
{
log.warn("Downloading {} failed with HTTP {}, retrying ({}/{})", savePath, response.statusCode(), attempt + 1, MAX_DOWNLOAD_ATTEMPTS);
} else
{
throwOnError(response);
}
} finally
{
deleteQuietly(savePath);
}
Thread.sleep(RETRY_DELAY_MILLIS * attempt);
}
}

private boolean isRetryableStatusCode(int statusCode)
{
return statusCode == 429 || statusCode >= 500;
}

private void deleteQuietly(Path path)
{
try
{
Files.deleteIfExists(path);
} catch (IOException e)
{
log.warn("Unable to remove incomplete file: {}", path);
}
}

public String fetchProject() throws IOException, InterruptedException
Expand Down Expand Up @@ -192,14 +244,8 @@ private void throwOnError(HttpResponse<?> httpResponse)
{
if (httpResponse.statusCode() != 200)
{
com.jayway.jsonpath.Configuration parseContext = com.jayway.jsonpath.Configuration
.defaultConfiguration()
.addOptions(Option.SUPPRESS_EXCEPTIONS);

Object responseBody = httpResponse.body();
String stringBody = safeCastHttpBodyToString(responseBody);
String message = JsonPath.using(parseContext).parse(stringBody).read(ERROR_MESSAGE_PATH);
if (message == null)
String message = tryReadErrorMessage(httpResponse);
if (StringUtils.isBlank(message))
{
message = "Unknown error, HTTP Status: " + httpResponse.statusCode();
}
Expand All @@ -208,6 +254,27 @@ private void throwOnError(HttpResponse<?> httpResponse)
}
}

private String tryReadErrorMessage(HttpResponse<?> httpResponse)
{
String stringBody = safeCastHttpBodyToString(httpResponse.body());
if (StringUtils.isBlank(stringBody))
{
return null;
}
try
{
com.jayway.jsonpath.Configuration parseContext = com.jayway.jsonpath.Configuration
.defaultConfiguration()
.addOptions(Option.SUPPRESS_EXCEPTIONS);
Object message = JsonPath.using(parseContext).parse(stringBody).read(ERROR_MESSAGE_PATH);
return message != null ? String.valueOf(message) : null;
} catch (Exception e)
{
log.debug("Unable to extract error message from response body", e);
return null;
}
}

private String safeCastHttpBodyToString(Object responseBody)
{
if (responseBody instanceof byte[] responseBodyBytes)
Expand All @@ -216,6 +283,15 @@ private String safeCastHttpBodyToString(Object responseBody)
} else if (responseBody instanceof String responseBodyString)
{
return responseBodyString;
} else if (responseBody instanceof Path responseBodyPath)
{
try
{
return Files.readString(responseBodyPath);
} catch (IOException e)
{
return "";
}
}
return "";
}
Expand Down
116 changes: 116 additions & 0 deletions src/test/java/io/simplelocalize/cli/client/SimpleLocalizeClientTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -272,4 +272,120 @@ void shouldDownloadAndTruncateBeforeWriting() throws Exception
//then
assertThat(Path.of(downloadPath)).hasContent("sample").isRegularFile();
}

@Test
void shouldThrowApiRequestExceptionWhenDownloadFailsWithEmptyBody()
{
//given
SimpleLocalizeClient client = new SimpleLocalizeClient(MOCK_SERVER_BASE_URL, "96a7b6ca75c79d4af4dfd5db2946fdd4");
mockServer.when(request()
.withMethod("GET")
.withPath("/s3/missing-file"),
Times.exactly(1))
.respond(
response()
.withStatusCode(403)
.withDelay(TimeUnit.MILLISECONDS, 200)
);

DownloadableFile downloadableFile = new DownloadableFile(MOCK_SERVER_BASE_URL + "/s3/missing-file", "common", null, null, null, null);
String downloadPath = "./junit/download-error/file.json";

//when & then
Assertions
.assertThatThrownBy(() -> client.downloadFile(downloadableFile, downloadPath))
.isInstanceOf(ApiRequestException.class)
.hasMessage("Unknown error, HTTP Status: 403");

assertThat(Path.of(downloadPath)).doesNotExist();
}

@Test
void shouldThrowApiRequestExceptionWithMessageWhenDownloadFailsWithJsonBody()
{
//given
SimpleLocalizeClient client = new SimpleLocalizeClient(MOCK_SERVER_BASE_URL, "96a7b6ca75c79d4af4dfd5db2946fdd4");
mockServer.when(request()
.withMethod("GET")
.withPath("/s3/expired-file"),
Times.exactly(1))
.respond(
response()
.withStatusCode(410)
.withContentType(MediaType.APPLICATION_JSON_UTF_8)
.withBody("{ \"msg\": \"link expired\" }")
.withDelay(TimeUnit.MILLISECONDS, 200)
);

DownloadableFile downloadableFile = new DownloadableFile(MOCK_SERVER_BASE_URL + "/s3/expired-file", "common", null, null, null, null);
String downloadPath = "./junit/download-error/expired.json";

//when & then
Assertions
.assertThatThrownBy(() -> client.downloadFile(downloadableFile, downloadPath))
.isInstanceOf(ApiRequestException.class)
.hasMessage("link expired");

assertThat(Path.of(downloadPath)).doesNotExist();
}

@Test
void shouldRetryDownloadOnServerError() throws Exception
{
//given
SimpleLocalizeClient client = new SimpleLocalizeClient(MOCK_SERVER_BASE_URL, "96a7b6ca75c79d4af4dfd5db2946fdd4");
mockServer.when(request()
.withMethod("GET")
.withPath("/s3/flaky-file"),
Times.exactly(2))
.respond(
response()
.withStatusCode(500)
);
mockServer.when(request()
.withMethod("GET")
.withPath("/s3/flaky-file"),
Times.exactly(1))
.respond(
response()
.withStatusCode(200)
.withContentType(MediaType.APPLICATION_JSON_UTF_8)
.withBody("{ \"key\": \"value\" }")
);

DownloadableFile downloadableFile = new DownloadableFile(MOCK_SERVER_BASE_URL + "/s3/flaky-file", "common", null, null, null, null);
String downloadPath = "./junit/download-retry/file.json";

//when
client.downloadFile(downloadableFile, downloadPath);

//then
assertThat(Path.of(downloadPath)).hasContent("{ \"key\": \"value\" }").isRegularFile();
}

@Test
void shouldGiveUpDownloadAfterMaxRetryAttempts()
{
//given
SimpleLocalizeClient client = new SimpleLocalizeClient(MOCK_SERVER_BASE_URL, "96a7b6ca75c79d4af4dfd5db2946fdd4");
mockServer.when(request()
.withMethod("GET")
.withPath("/s3/broken-file"),
Times.exactly(3))
.respond(
response()
.withStatusCode(503)
);

DownloadableFile downloadableFile = new DownloadableFile(MOCK_SERVER_BASE_URL + "/s3/broken-file", "common", null, null, null, null);
String downloadPath = "./junit/download-retry/broken.json";

//when & then
Assertions
.assertThatThrownBy(() -> client.downloadFile(downloadableFile, downloadPath))
.isInstanceOf(ApiRequestException.class)
.hasMessage("Unknown error, HTTP Status: 503");

assertThat(Path.of(downloadPath)).doesNotExist();
}
}