Add FileSinkCommitStrategy

This hopefully clears up, at least for the use of the FileSinkWriteExt
trait the relationship between `auto_commit` and `roll_time`. There is
no default implementaion for this option, as all options have
implications that should be considered.

file_store/src/file_sink.rs

@@ -253,12 +253,19 @@ pub struct FileSink<T> {
     target_path: PathBuf,
     tmp_path: PathBuf,
     prefix: String,
+    /// Maximum file size in bytes. If a single write would cause this limit to
+    /// be exceeded, the `active_sink` is rolled.
     max_size: usize,
+    /// Window within which writes can occur to `active_sink`. `roll_time` is
+    /// not checked during writing, so a file may contain items exceeding the
+    /// window of `roll_time`.
     roll_time: Duration,
 
     messages: MessageReceiver<T>,
     file_upload: FileUpload,
     staged_files: Vec<PathBuf>,
+    /// 'commit' the file to s3 automatically when either the `roll_time` is
+    /// surpassed, or `max_size` would be exceeded by an incoming message.
     auto_commit: bool,
 
     active_sink: Option<ActiveSink>,

file_store/src/traits/file_sink_write.rs

@@ -14,6 +14,22 @@ use helium_proto::{
 
 pub const DEFAULT_ROLL_TIME: Duration = Duration::from_secs(DEFAULT_SINK_ROLL_SECS);
 
+#[derive(Copy, Clone, PartialEq, Eq)]
+pub enum FileSinkCommitStrategy {
+    /// Writer must manually call [`FileSinkClient::commit()`] for files to be uploaded.
+    /// Files will be collected into tmp storage on `DEFAULT_ROLL_TIME` basis.
+    Manual,
+    /// Writer must manually call [`FileSinkClient::commit()`] for files to be uploaded.
+    /// Files will be collected into tmp storage on provided `roll_time` basis.
+    ManualRollTime(Duration),
+    /// Files will be automatically uploaded when
+    /// [`FileSinkBuilder::max_size()`] is exceeded, or [`DEFAULT_ROLL_TIME`] has elapsed.
+    Automatic,
+    /// Files will be automatically uploaded when
+    /// [`FileSinkBuilder::max_size()`] is exceeded, or provided `roll_time` has elapsed.
+    AutomaticRollTime(Duration),
+}
+
 #[async_trait::async_trait]
 pub trait FileSinkWriteExt
 where
@@ -22,14 +38,10 @@ where
     const FILE_PREFIX: &'static str;
     const METRIC_SUFFIX: &'static str;
 
-    // The `auto_commit` option and `roll_time` option are incompatible with
-    // each other. It doesn't make sense to roll a file every so often _and_
-    // commit it every time something is written. If a roll_time is provided,
-    // `auto_commit` is set to false.
     async fn file_sink(
         target_path: &Path,
         file_upload: FileUpload,
-        roll_time: Option<Duration>,
+        commit_strategy: FileSinkCommitStrategy,
         metric_prefix: &str,
     ) -> Result<(FileSinkClient<Self>, FileSink<Self>)> {
         let builder = FileSinkBuilder::new(
@@ -39,10 +51,19 @@ where
             format!("{}_{}", metric_prefix, Self::METRIC_SUFFIX),
         );
 
-        let builder = if let Some(duration) = roll_time {
-            builder.auto_commit(false).roll_time(duration)
-        } else {
-            builder.auto_commit(true)
+        let builder = match commit_strategy {
+            FileSinkCommitStrategy::Manual => {
+                builder.auto_commit(false).roll_time(DEFAULT_ROLL_TIME)
+            }
+            FileSinkCommitStrategy::ManualRollTime(roll_time) => {
+                builder.auto_commit(false).roll_time(roll_time)
+            }
+            FileSinkCommitStrategy::Automatic => {
+                builder.auto_commit(true).roll_time(DEFAULT_ROLL_TIME)
+            }
+            FileSinkCommitStrategy::AutomaticRollTime(roll_time) => {
+                builder.auto_commit(true).roll_time(roll_time)
+            }
         };
 
         let file_sink = builder.create().await?;

file_store/src/traits/mod.rs

@@ -5,7 +5,7 @@ mod msg_timestamp;
 mod msg_verify;
 mod report_id;
 
-pub use file_sink_write::{FileSinkWriteExt, DEFAULT_ROLL_TIME};
+pub use file_sink_write::{FileSinkCommitStrategy, FileSinkWriteExt, DEFAULT_ROLL_TIME};
 pub use msg_bytes::MsgBytes;
 pub use msg_decode::MsgDecode;
 pub use msg_timestamp::{MsgTimestamp, TimestampDecode, TimestampEncode};