Module `Capnp_unix.IO`

exception Unsupported_message_frame

module WriteContext : sig ... end

module ReadContext : sig ... end

val create_write_context_for_fd : 
  ?restart:bool ->
  compression:Capnp.Codecs.compression_t ->
  Unix.file_descr ->
  Unix.file_descr WriteContext.t

create_write_context_for_fd ~compression fd creates a context for writing messages to the given file descriptor using the specified compression format. If restart is set to true (default), then writes failing with error code Unix.EINTR will be automatically restarted.

val create_write_context_for_channel : 
  compression:Capnp.Codecs.compression_t ->
  Pervasives.out_channel ->
  Pervasives.out_channel WriteContext.t

create_write_context_for_channel ~compression chan creates a context for writing messages to the given buffered output channel using the specified compression format.

val create_read_context_for_fd : 
  ?restart:bool ->
  compression:Capnp.Codecs.compression_t ->
  Unix.file_descr ->
  Unix.file_descr ReadContext.t

create_read_context_for_fd ~compression fd creates a context for reading messages from the given file descriptor using the specified compression method. If restart is set to true (default), then writes failing with error code Unix.EINTR will be automatically restarted.

val create_read_context_for_channel : 
  compression:Capnp.Codecs.compression_t ->
  Pervasives.in_channel ->
  Pervasives.in_channel ReadContext.t

create_read_context_for_channel ~compression chan creates a context for reading messages from the given input channel using the specified compression method.

val write_message_to_fd : 
  ?restart:bool ->
  compression:Capnp.Codecs.compression_t ->
  'cap Capnp.Message.BytesMessage.Message.t ->
  Unix.file_descr ->
  unit

write_message_to_fd ~compression message fd writes the specified message to the given file descriptor, using the specified compression method. If restart is set to true (default), then writes failing with error code Unix.EINTR will be automatically restarted.

EAGAIN/EWOULDBLOCK are handled automatically.

raises Unix.Unix_error
if a write fails

val write_message_to_channel : 
  compression:Capnp.Codecs.compression_t ->
  'cap Capnp.Message.BytesMessage.Message.t ->
  Pervasives.out_channel ->
  unit

write_message_to_channel ~compression message chan writes the specified message to the given buffered I/O channel, using the specified compression method.

val write_message_to_file : 
  ?perm:int ->
  compression:Capnp.Codecs.compression_t ->
  'cap Capnp.Message.BytesMessage.Message.t ->
  string ->
  unit

write_message_to_file ~compression message filename writes the specified message to a file with the given filename, using the requested compression method. The optional perm specifies the file creation mode, in case a new file must be created.

val write_message_to_file_robust : 
  ?perm:int ->
  compression:Capnp.Codecs.compression_t ->
  'cap Capnp.Message.BytesMessage.Message.t ->
  string ->
  unit

As write_message_to_file, but the file is constructed transactionally by writing to a temporary file and renaming to the filename, and Unix.fsync is used carefully to ensure durability of the write.

The overhead of rename and fsync may lead to reduced throughput relative to write_message_to_file.

raises Unix.Unix_error
if write, fsync, or rename operations fail.

val read_single_message_from_fd : 
  ?restart:bool ->
  compression:Capnp.Codecs.compression_t ->
  Unix.file_descr ->
  Capnp.Message.rw Capnp.Message.BytesMessage.Message.t option

read_single_message_from_fd ~compression fd attempts to read a single message from the specified file descriptor, using the given compression method. If restart is set to true (default), then writes failing with error code Unix.EINTR will be automatically restarted.

EAGAIN/EWOULDBLOCK are handled automatically.

This function is appropriate to use only when 0 or 1 messages are expected to be available from the descriptor; if additional messages are available, some message data could be lost. Use create_XXX_read_context_for_fd to correctly handle a stream of messages.

returns
Some message, or None if end-of-file was reached before a message could be decoded.

raises Unix.Unix_error
if a read fails

raises Unsupported_message_frame
if the frame header describes a segment count or segment size that is too large for the implementation

val read_single_message_from_channel : 
  compression:Capnp.Codecs.compression_t ->
  Pervasives.in_channel ->
  Capnp.Message.rw Capnp.Message.BytesMessage.Message.t option

read_single_message_from_channel ~compression chan attempts to read a single message from the specified input channel, using the given compression method.

This function is appropriate to use only when 0 or 1 messages are expected to be available from the channel; if additional messages are available, some message data could be lost. Use create_XXX_read_context_for_channel to correctly handle a stream of messages.

returns
Some message, or None if end-of-file was reached before a message could be decoded.

raises Unsupported_message_frame
if the frame header describes a segment count or segment size that is too large for the implementation

val read_message_from_file : 
  compression:Capnp.Codecs.compression_t ->
  string ->
  Capnp.Message.rw Capnp.Message.BytesMessage.Message.t option

read_message_from_file ~compression filename attempts to read a message from the file with the given filename, using the requested compression method.

returns
Some message, or None if the file does not contain a complete message frame.

Install

Dune Dependency

Authors

Maintainers

Sources

doc/capnp.unix/Capnp_unix/IO/index.html

Module `Capnp_unix.IO`

package capnp

Install

Dune Dependency

Authors

Maintainers

Sources

doc/capnp.unix/Capnp_unix/IO/index.html

Module Capnp_unix.IO

Module `Capnp_unix.IO`