Struct ShardManager 

pub struct ShardManager { /* private fields */ }

Manages time-sharded event files in a .bones repository.

The shard manager handles:

• Directory initialization
• Shard rotation on month boundaries
• Atomic append with advisory locking
• Monotonic clock maintenance
• Torn-write recovery
• Replay (reading all shards chronologically)
• Sealed shard manifest generation

Implementations

impl ShardManager

pub fn new(bones_dir: impl Into<PathBuf>) -> Self

Create a new ShardManager for the given .bones directory.

Does not create directories on construction; call init or ensure_dirs first if needed.

pub fn events_dir(&self) -> PathBuf

Path to the events directory.

pub fn lock_path(&self) -> PathBuf

Path to the advisory lock file.

pub fn clock_path(&self) -> PathBuf

Path to the monotonic clock file.

pub fn current_symlink(&self) -> PathBuf

Path to the current.events symlink.

pub fn shard_filename(year: i32, month: u32) -> String

Generate the shard filename for a given year and month.

pub fn shard_path(&self, year: i32, month: u32) -> PathBuf

Path to a specific shard file.

pub fn manifest_path(&self, year: i32, month: u32) -> PathBuf

Path to a manifest file for a given shard.

pub fn ensure_dirs(&self) -> Result<(), ShardError>

Create the .bones/events/ and .bones/cache/ directories if they don’t exist. Idempotent.

Errors

Returns ShardError::InitFailed if directory creation fails.

pub fn init(&self) -> Result<(i32, u32), ShardError>

Initialize the shard directory and create the first shard file with the standard header if no shards exist.

Returns the (year, month) of the active shard.

Errors

Returns ShardError on I/O failure or if directories cannot be created.

pub fn list_shards(&self) -> Result<Vec<(i32, u32)>, ShardError>

List all shard files in chronological order as (year, month) pairs.

Shard filenames must match YYYY-MM.events. Invalid filenames are silently skipped.

Errors

Returns ShardError::Io if the directory cannot be read.

pub fn active_shard(&self) -> Result<Option<(i32, u32)>, ShardError>

Get the active (most recent) shard, if any.

Errors

Returns ShardError::Io if the directory cannot be read.

pub fn create_shard(&self, year: i32, month: u32) -> Result<PathBuf, ShardError>

Create a new shard file with the standard header.

Returns the path of the created file. Does nothing if the file already exists.

Errors

Returns ShardError::Io if the file cannot be written.

pub fn update_symlink(&self, year: i32, month: u32) -> Result<(), ShardError>

Update the current.events symlink to point to the given shard.

Errors

Returns ShardError::Io if the symlink cannot be created.

pub fn rotate_if_needed(&self) -> Result<(i32, u32), ShardError>

Check if the current month differs from the active shard’s month. If so, seal the old shard (generate manifest) and create a new one.

Returns the (year, month) of the now-active shard.

Errors

Returns ShardError on I/O failure during rotation.

pub fn write_manifest( &self, year: i32, month: u32, ) -> Result<ShardManifest, ShardError>

Generate and write a manifest file for a sealed shard.

Errors

Returns ShardError::Io if the shard file cannot be read or the manifest cannot be written.

pub fn read_manifest( &self, year: i32, month: u32, ) -> Result<Option<ShardManifest>, ShardError>

Read a manifest file if it exists.

Errors

Returns ShardError::Io if the manifest file exists but cannot be read.

pub fn append( &self, line: &str, durable: bool, lock_timeout: Duration, ) -> Result<i64, ShardError>

Append an event line to the active shard.

This method:

1. Acquires the repo-wide advisory lock.
2. Rotates shards if the month has changed.
3. Reads and updates the monotonic clock.
4. Appends the line using O_APPEND + write_all + flush.
5. Optionally calls sync_data if durable is true.
6. Releases the lock.

The line must be a complete TSJSON line ending with \n.

Returns the monotonic timestamp used.

Errors

Returns ShardError::Lock if the lock cannot be acquired within lock_timeout, or ShardError::Io on write failure.

pub fn append_raw( &self, year: i32, month: u32, line: &str, ) -> Result<(), ShardError>

Append a raw line without locking or clock update.

Used internally and in tests. The caller is responsible for holding the lock and managing the clock.

Errors

Returns ShardError::Io on write failure.

pub fn read_clock(&self) -> Result<i64, ShardError>

Read the current monotonic clock value.

Returns 0 if the clock file doesn’t exist.

Errors

Returns ShardError::Io if the clock file exists but cannot be read.

pub fn next_timestamp(&self) -> Result<i64, ShardError>

Compute the next monotonic timestamp and write it to the clock file.

next = max(system_time_us, last + 1)

The caller must hold the repo lock.

Errors

Returns ShardError::Io if the clock file cannot be read or written.

pub fn recover_torn_writes(&self) -> Result<Option<u64>, ShardError>

Scan the active shard for torn writes and truncate incomplete trailing lines.

A torn write leaves a partial line (no terminating \n) at the end of the file. This method finds the last complete newline and truncates everything after it.

Returns Ok(Some(bytes_truncated)) if a torn write was repaired, or Ok(None) if the file was clean.

Errors

Returns ShardError::Io if the shard file cannot be read or truncated.

pub fn replay(&self) -> Result<String, ShardError>

Read all event lines from all shards in chronological order.

Shards are read in lexicographic order (YYYY-MM sorts correctly). Returns the concatenated content of all shard files.

Errors

Returns ShardError::Io if any shard file cannot be read.

pub fn read_shard(&self, year: i32, month: u32) -> Result<String, ShardError>

Read event lines from a specific shard.

Errors

Returns ShardError::Io if the shard file cannot be read.

pub fn total_content_len(&self) -> Result<usize, ShardError>

Compute the total concatenated byte size of all shards without reading their full contents.

This is used for advancing the projection cursor without paying the cost of a full replay.

Errors

Returns ShardError::Io if any shard file metadata cannot be read.

pub fn replay_from_offset( &self, offset: usize, ) -> Result<(String, usize), ShardError>

Read shard content starting from the given absolute byte offset in the concatenated shard sequence.

Sealed shards that end entirely before offset are skipped without reading their contents — only their file sizes are stat(2)’d. Only content from offset onward is returned, bounding memory use to new/unseen events rather than the full log.

Returns (new_content, total_len) where:

• new_content is the bytes from offset to the end of all shards.
• total_len is the total byte size of all shards concatenated (usable as the new cursor offset after processing new_content).

Errors

Returns ShardError::Io if shard metadata or file reads fail.

pub fn read_content_range( &self, start_offset: usize, end_offset: usize, ) -> Result<String, ShardError>

Read bytes from the concatenated shard sequence in [start_offset, end_offset).

Only shards that overlap with the requested range are read. Shards entirely outside the range are stat(2)’d but not read.

This is used to read a small window around the projection cursor for hash validation without loading the full shard content.

Errors

Returns ShardError::Io if any shard file cannot be read.

pub fn event_count(&self) -> Result<u64, ShardError>

Count event lines across all shards (excluding comments and blanks).

Errors

Returns ShardError::Io if any shard file cannot be read.

pub fn replay_lines( &self, ) -> Result<impl Iterator<Item = Result<(usize, String)>>, ShardError>

Iterate over all event lines across all shards.

Yields (absolute_offset, line_content) pairs.

Errors

Returns ShardError::Io if directory or shard reading fails.

pub fn replay_lines_from_offset( &self, offset: usize, ) -> Result<impl Iterator<Item = Result<(usize, String)>>, ShardError>

Iterate over event lines starting from a given absolute byte offset.

Yields (absolute_offset, line_content) pairs.

Errors

Returns ShardError::Io if directory or shard reading fails.

pub fn is_empty(&self) -> Result<bool, ShardError>

Check if the repository has any event shards.

Errors

Returns ShardError::Io if the events directory cannot be read.