metricsd: Persist the metrics to disk periodically.
Every now and then (5 minutes by default), the uploader will persist the
current metrics to disk to avoid losing them in case we exit
unexpectedly (reboot or crash).
When starting up, metricsd will load the previously saved log and resume
the metrics collection from there.
Bug: 25670584
Test: Unit tests.
Test: manual: restart metricsd. The saved log is detected and parsed
correctly.
Test: manual: Send a sample to metricsd, send SIGTERM to metricsd, the
log is saved to disk, metricsd restarts and picks up the log where it
left.
Change-Id: I4cefc62c7ea1fa51333d84d8a7ba0a2e9c7fd58f
diff --git a/metricsd/constants.h b/metricsd/constants.h
index 4815888..b702737 100644
--- a/metricsd/constants.h
+++ b/metricsd/constants.h
@@ -26,6 +26,7 @@
static const char kMetricsServer[] = "https://clients4.google.com/uma/v2";
static const char kConsentFileName[] = "enabled";
static const char kStagedLogName[] = "staged_log";
+static const char kSavedLogName[] = "saved_log";
static const char kFailedUploadCountName[] = "failed_upload_count";
static const char kDefaultVersion[] = "0.0.0.0";