Struct AeronCnc

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pub struct AeronCnc { /* private fields */ }

Implementations§

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impl AeronCnc

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pub fn new_zeroed_on_heap() -> Self

creates zeroed struct where the underlying c struct is on the heap

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pub fn new_zeroed_on_stack() -> Self

creates zeroed struct where the underlying c struct is on the stack (Use with care)

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pub fn constants( &self, constants: &AeronCncConstants, ) -> Result<i32, AeronCError>

Fetch the sets of constant values associated with this command and control file.

§Parameters

constants user supplied structure to hold return values.

§Return

0 on success, -1 on failure.

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pub fn get_constants(&self) -> Result<AeronCncConstants, AeronCError>

Fetch the sets of constant values associated with this command and control file.

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pub fn filename(&self) -> &str

Get the current file name of the cnc file.

§Return

name of the cnc file

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pub fn to_driver_heartbeat(&self) -> i64

Gets the timestamp of the last heartbeat sent to the media driver from any client.

§Return

last heartbeat timestamp in ms.

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pub fn error_log_read<AeronErrorLogReaderFuncHandlerImpl: AeronErrorLogReaderFuncCallback>( &self, callback: Option<&Handler<AeronErrorLogReaderFuncHandlerImpl>>, since_timestamp: i64, ) -> usize

Reads the current error log for this driver.

§Parameters

callback called for every distinct error observation
clientd client data to be passed to the callback
since_timestamp only return errors after this timestamp (0 returns all)

§Return

the number of distinct errors seen

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pub fn error_log_read_fn<AeronErrorLogReaderFuncHandlerImpl: FnMut(i32, i64, i64, &str)>( &self, callback: AeronErrorLogReaderFuncHandlerImpl, since_timestamp: i64, ) -> usize

Reads the current error log for this driver.

§Parameters

callback called for every distinct error observation
clientd client data to be passed to the callback
since_timestamp only return errors after this timestamp (0 returns all)

§Return

the number of distinct errors seen

Stack-borrowed closure (_fn variant): the FnMut closure lives on the caller’s stack and is borrowed for this call only — the callback fires synchronously inside the call, so nothing is heap-allocated, nothing is stored, and the closure may borrow local state. Prefer this over the retained Handler-based form on the hot path; only generated for callbacks the C client does not retain (i.e. not stored for later firing).

§Panics

A panic inside the closure cannot unwind across the extern "C" callback boundary and aborts the process (since Rust 1.81). Return early instead of panicking in production fragment handlers.

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pub fn counters_reader(&self) -> AeronCountersReader

Gets a counters reader for this command and control file. This does not need to be closed manually, resources are tied to the instance of aeron_cnc.

§Return

pointer to a counters reader.

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pub fn loss_reporter_read<AeronLossReporterReadEntryFuncHandlerImpl: AeronLossReporterReadEntryFuncCallback>( &self, entry_func: Option<&Handler<AeronLossReporterReadEntryFuncHandlerImpl>>, ) -> Result<i32, AeronCError>

Read all of the data loss observations from the report in the same media driver instances as the cnc file.

§Parameters

entry_func callback for each observation found

§Return

-1 on failure, number of observations on success (could be 0).

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pub fn loss_reporter_read_fn<AeronLossReporterReadEntryFuncHandlerImpl: FnMut(i64, i64, i64, i64, i32, i32, &str, &str)>( &self, entry_func: AeronLossReporterReadEntryFuncHandlerImpl, ) -> Result<i32, AeronCError>

Read all of the data loss observations from the report in the same media driver instances as the cnc file.

§Parameters

entry_func callback for each observation found

§Return

-1 on failure, number of observations on success (could be 0).

Stack-borrowed closure (_fn variant): the FnMut closure lives on the caller’s stack and is borrowed for this call only — the callback fires synchronously inside the call, so nothing is heap-allocated, nothing is stored, and the closure may borrow local state. Prefer this over the retained Handler-based form on the hot path; only generated for callbacks the C client does not retain (i.e. not stored for later firing).

§Panics

A panic inside the closure cannot unwind across the extern "C" callback boundary and aborts the process (since Rust 1.81). Return early instead of panicking in production fragment handlers.

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pub fn resolve_filename( directory: &CStr, filename_buffer: &mut [u8], ) -> Result<i32, AeronCError>

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pub fn get_inner(&self) -> *mut aeron_cnc_t

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pub unsafe fn get_inner_mut(&self) -> &mut aeron_cnc_t

Mutable access to the underlying C struct, minted from &self: nothing prevents two live &mut at once, so the caller must ensure exclusive access for the lifetime of the returned reference.

§Safety

No other reference (& or &mut) to the underlying struct may be alive while the returned &mut is in use.

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pub fn get_inner_ref(&self) -> &aeron_cnc_t

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impl AeronCnc

Counters and Control (CnC) file — the shared-memory interface between the media driver and its clients.

The CnC file contains:

Counters: stream positions, recording positions, liveness indicators, and application-defined counters.
Error log: a ring-buffer of recent driver/client errors.
Loss reporter: observed packet-loss entries.
To-driver / to-clients command buffers.

AeronCnc is a read-only view of the CnC file — use it to inspect driver state, dump counters, or read the error log (the upstream aeron_stat, error_stat, and loss_stat tools all do this).

§Two access patterns

Scoped read (zero allocation, preferred for one-shot queries):

AeronCnc::read(driver_ctx.get_dir(), |cnc| {
    cnc.foreach_counter_fn(|value, id, type_id, key, label| {
        println!("{id}: {label} = {value}");
    });
})?;

Opens the CnC file, runs the closure, closes — the resource wrapper lives on the stack and is freed immediately after.

Owned handle (for repeated polling, e.g. a stats dashboard):

let cnc = AeronCnc::open(driver_ctx.get_dir())?;
loop {
    let heartbeat = cnc.to_driver_heartbeat();
    // ... poll counters, error log, etc. ...
    sleep(Duration::from_secs(1));
}
// closed on drop

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pub fn read( aeron_dir: &CStr, handler: impl FnMut(&mut AeronCnc), ) -> Result<(), AeronCError>

Open the CnC file, run handler, close — zero heap allocation for the resource wrapper (the C struct is stack-borrowed). Preferred for one-shot reads (dump counters, print the error log). Accepts &CStr so c"" literals work directly.

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pub fn open(aeron_dir: &CStr) -> Result<AeronCnc, AeronCError>

Open the CnC file and return an owned handle you can store and poll repeatedly (e.g. a monitoring loop). Allocates the resource wrapper on the heap; closed on drop. Accepts &CStr so c"" literals work.

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