Add file rotation

README.md

@@ -14,7 +14,7 @@ This project is under the MIT license.
 | --- | --- |
 | REPL for testing | Yes |
 | Append Only Log Structured Storage | Yes |
-| Log Rotation | No |
+| Log Rotation | Yes |
 | CRC Validation | Yes |
 | Startup KeyDir rebuilding | Yes |
 | Log Compaction | No |
@@ -34,7 +34,7 @@ Note that at runtime the entire keyspace is maintained in memory so enough memor
 
 The data on disk is organized into files with a capped size that is configurable using the environment variables listed below.  Files are rotated as they reach this size.
 
-The previously stored and compacted files are named `<timestamp>`, where `<timestamp>` is the string representation of seconds since epoch.  The file currently being written is named `0`.
+The previously stored and compacted files are named `<timestamp>`, where `<timestamp>` is the string representation of milliseconds since epoch.  The file currently being written is named with the most recent timestamp value.
 
 ## Binary Entry File Format
 
@@ -134,15 +134,15 @@ The following environment variables provide configuration values for the databas
 
 #### Optional Environment Variables
 
-`RUSTCASK_MAX_FILE_SIZE_MB` - The maximum file size cap, in MB.  Defaults to 4 MB if not present.
+`RUSTCASK_ROTATE_ACTIVE_FILE_AFTER_BYTES` - The number of bytes after which to rotate the active file.  Defaults to 4 MiB if not present.
 
 ## Running the Application
 
 First, configure a local `.env` file to contain the following environment variables:
 
 ```
 RUSTCASK_FILE_PATH=<absolute path to file storage for database data>
-RUSTCASK_MAX_FILE_SIZE_MB=<integer file size, in MB>
+RUSTCASK_ROTATE_ACTIVE_FILE_AFTER_BYTES=<integer file size, in bytes>
 RUST_LOG=<log level>
 ```
 

src/main.rs

@@ -19,7 +19,7 @@ use std::{
 };
 use tracing_subscriber::EnvFilter;
 
-const DEFAULT_RUSTCASK_MAX_FILE_SIZE_MB: &str = "4";
+const DEFAULT_RUSTCASK_ROTATE_ACTIVE_FILE_AFTER_BYTES: u64 = 4194304;
 
 #[derive(Debug)]
 enum ReplError {
@@ -45,7 +45,7 @@ fn main() -> Result<(), ReplError> {
     #[cfg(feature = "mock")]
     let db = MockDatabase::open();
     #[cfg(not(feature = "mock"))]
-    let db = RustcaskDatabase::open(settings.file_path).map_err(|e| ReplError::DatabaseError(e))?;
+    let db = RustcaskDatabase::open(settings.file_path, settings.rotate_active_file_after_bytes).map_err(|e| ReplError::DatabaseError(e))?;
 
     cmd_loop(db)
 }
@@ -64,12 +64,11 @@ fn load_settings() -> Result<Settings, ReplError> {
         )));
     }
 
-    let max_file_size_env_value = env::var("RUSTCASK_MAX_FILE_SIZE_MB")
-        .unwrap_or(DEFAULT_RUSTCASK_MAX_FILE_SIZE_MB.into())
-        .parse::<u8>()
-        .expect("RUSTCASK_MAX_FILE_SIZE_MB did not parse into a u8");
+    let rotate_active_file_after_bytes_env_value = env::var("RUSTCASK_ROTATE_ACTIVE_FILE_AFTER_BYTES")
+        .map_or(Ok(DEFAULT_RUSTCASK_ROTATE_ACTIVE_FILE_AFTER_BYTES), |v| v.parse::<u64>())
+        .expect("RUSTCASK_ROTATE_ACTIVE_FILE_AFTER_BYTES did not parse into a u64");
 
-    Ok(Settings::new(file_path, max_file_size_env_value))
+    Ok(Settings::new(file_path, rotate_active_file_after_bytes_env_value))
 }
 
 #[tracing::instrument(skip(db))]