efl/src/lib/ecore/efl_io_copier.eo

import eina_types;

class Efl.Io.Copier (Efl.Loop_User, Efl.Io.Closer) {
    [[Copy from an @Efl.Io.Reader source to @Efl.Io.Writer destination.

      During usage it will keep reference to @.source and
      @.destination objects, automatically relasing them on
      destructor.

      By default the read-write process is done based on fixed-size
      chunks (@.read_chunk_size), however if @.line_delimiter is set,
      the behavior changes to wait for such delimiter or a maximum
      buffer limit is reached (@.buffer_limit).

      While a @.source is mandatory for the copier to operate
      properly, the @.destination is optional: if it's not provided,
      all read data is stored in an internal buffer that can be
      retrieved using @.binbuf_steal, usually called when one of
      "data", "line" or "done" events are emitted.

      Most important events:

        - The "data" event is general and notifies some data was
          written to @.destination (if any, otherwise it will be
          reported for data when it's read from @.source).

        - The "line" event is only emitted when @.line_delimiter is
          set and not empty. It's simiar to "data".

        - The "done" event is emitted if @.source is
          @Efl.Io.Reader.eos $true and all data was written to
          @.destination (if any, otherwise it will be reported when
          all data was read from @.source).

        - The "error" event is reported if the @Efl.Io.Reader.read,
          @Efl.Io.Writer.write or some other internal error happened,
          like out of memory. Another common error is ETIMEDOUT if
          @.timeout_inactivity is set.

      A copier is handful to simplify common I/O use cases, such as:

        - Read a file or download content to memory: provide only the
          source and wait for "done" event, calling @.binbuf_steal
          afterwards.

        - Download content to disk: provide a network socket as source
          and use @Efl.Io.File as destination, then wait for "done"
          event.

        - Link two I/O streams: provide both source and destination
          streams, such as @Efl.Io.Stdin and @Efl.Io.Stdout, or some
          network socket. As data is received from source it will be
          copied to destination in an endless (asynchronous) loop. You
          may monitor for "done" if the source may be closed.

      If @Efl.Io.Closer.close is called, then it will be called on
      @.source and @.destination if they implement those interfaces.

      @Efl.Io.Closer.close_on_exec and
      @Efl.Io.Closer.close_on_destructor are respected and applied to
      both source and destination. Both default to $true.

      @since 1.19
    ]]

    methods {
        @property source {
           [[Copier source object.

             The source object must implement the @Efl.Io.Reader
             interface and will provide data to the copier, thus it
             must be provided in order for the copier to work.

             The copier will monitor @Efl.Io.Reader.can_read property
             and "can_read,changed" event. When it's $true, then a
             chunk up to @.read_chunk_size is read using
             @Efl.Io.Reader.read into an intermediate storage buffer
             that can grow up to @.buffer_limit.

             If there is a @.destination, the read data is written
             there and afterwards "data" and "line" events are
             dispatched. If no destination, it's accumulated in the
             internal storage and "data" and "line" events are
             dispatched immediately.

             If there is a @.line_delimiter set, then copier will use
             that in order to attempt to write a full line at a time,
             including the delimiter. Exceptions may be if the
             @.source object emitted "eos" and there is no trailing
             delimiter (ie: missing trailing newline in files), or the
             @.buffer_limit was reached.

             Once @Efl.Io.Reader.eos is $true or "eos" event happen,
             then the read process is over. If there is no
             @.destination set, then the process is over and "done"
             event is called. If there is a @.destination, then all
             data must be flushed to it, draining the internal
             intermediate storage, before "done" event is emitted.

             If the source object implements @Efl.Io.Sizer interface,
             then the @.progress will report the total size. If the
             destination object also implements @Efl.Io.Sizer, then it
             will be resized to match the source size, providing the
             hint that may enhance performance (like pre-allocating
             the total amount and avoid dynamic resize).

             If the source object implements @Efl.Io.Closer and it's
             not closed, it will be closed when the copier itself
             is. This may happen, for example, when the copier is
             deleted and @Efl.Io.Closer.close_on_destructor is $true
             (the default).

             Common source classes are @Efl.Io.Buffer (if fixed data
             exists in memory), @Efl.Io.Queue (used to stream
             in-memory data) and @Efl.Io.File (data is present in the
             file system). Networking classes are also common source
             objects.
           ]]
           get {
           }
           set {
                [[Constructor-only property to set where to read data from]]
           }
           values {
                source: Efl.Io.Reader; [[@Efl.Io.Reader source]]
           }
        }

        @property destination {
           [[Copier destination object.

             If set it must implement @Efl.Io.Writer interface and
             will receive read data once @Efl.Io.Writer.can_write
             reports $true, this is monitored using
             "can_write,changed" event.

             The copier will attempt to write all internal
             intermediate storage data at once, however the
             destination object may consume less. The actual data
             written is emitted in the "data" and "line" events.

             If there is a @.line_delimiter set, then copier will use
             that in order to attempt to write a full line at a time,
             including the delimiter. Exceptions may be if the
             @.source object emitted "eos" and there is no trailing
             delimiter (ie: missing trailing newline in files), or the
             @.buffer_limit was reached.

             If @.source is flagged "eos" and all data was written to
             destination, then "done" event is emitted.

             If destination is not set (ie: NULL), then data is kept
             in a internal @Eina.Binbuf, that can be stolen with
             @.binbuf_steal once "data" or "line" events are
             emitted. It is allowed as a shortcut to easily drain
             readers and store all data in memory, not requiring an
             @Efl.Io.Buffer or @Efl.Io.Copier to be used -- a source
             and a copier are enough.

             If both source and destination object implements
             @Efl.Io.Sizer, then destination will be resized to match
             the source size, providing the hint that may enhance
             performance (like pre-allocating the total amount and
             avoid dynamic resize).

             If the destination object implements @Efl.Io.Closer and it's
             not closed, it will be closed when the copier itself
             is. This may happen, for example, when the copier is
             deleted and @Efl.Io.Closer.close_on_destructor is $true
             (the default).

             Common destination classes are @Efl.Io.Buffer (better to
             wait for all data in memory), @Efl.Io.Queue (to handle
             streaming protocols) and @Efl.Io.File (stores data to
             disk). Networking classes are also common destination
             objects.
           ]]
           get {
           }
           set {
                [[Constructor-only property to set where to write data to]]
           }
           values {
                destination: Efl.Io.Writer; [[@Efl.Io.Writer destination]]
           }
        }

        @property line_delimiter {
            [[If there is a line delimiter, the reads will buffer/queue up to the line delimiter before calling @Efl.Io.Writer.write on the @.destination and the event line is emitted with current line. The line may include the delimiter, unless it's end-of-stream on @.source or @.buffer_limit was reached.]]
            get { }
            set {
               [[Changes line delimiter to use. If empty, no delimiter is to be used]]
            }
            values {
                slice: const(Eina.Slice); [[The contents may contain \0 and will be copied]]
            }
        }

        @property buffer_limit {
           [[Copier buffer limit property, in bytes.

             During the read-write cycle, an intermediate storage
             buffer is used. By default it's zero -- unlimited, and
             will grow as needed if @.source provides data and
             @.destination do not consume it (or if there is no
             @.destination).

             However when reading data from untrusted sources, like
             network, one can exhaust the system memory by flooding
             the copier. In such cases, using a buffer limit is
             recommended.

             When the buffer limit is reached, the copier will pause
             reading data from @.source until @.destination consumes
             it. If there is no @.destination set, user should call
             @.binbuf_steal to consume data and reset buffer usage.

             Setting a buffer limit smaller than current
             @.read_chunk_size will automatically change
             @.read_chunk_size to the new buffer limit.
           ]]
           get {
           }
           set {
                [[Constructor-only property to set buffer limit. 0 is unlimited]]
           }
           values {
                size: size; [[Defines a maximum buffer limit, or 0 to allow unlimited amount of bytes]]
           }
        }

        @property read_chunk_size {
           [[Copier read chunk size property, in bytes.

             When a @.source is flagged with @Efl.Io.Reader.can_read
             $true, data will be read using @Efl.Io.Reader.read into
             an intermediate buffer of this size.

             Setting this value large enough may reduce number of
             @Efl.Io.Reader.read, improving performance at the expense
             of more memory consumption.

             This value is bounded by @.buffer_limit if it's set.

             By default it's 4096.
           ]]
           get {
           }
           set {
                [[Set chunk size for each basic @Efl.Io.Reader.read operation.]]
           }
           values {
                size: size; [[This is the chunk size to use for read operations]]
           }
        }

        @property progress {
            [[Progress for read and write.

              Reports value read from @.source, written to
              @.destination and the total, if the source implements
              @Efl.Io.Sizer.
            ]]
            get {
            }
            values {
                read: uint64 @optional; [[Amount of bytes read from source]]
                written: uint64 @optional; [[Amount of bytes written to destination]]
                total: uint64 @optional; [[If @.source is an Efl.Io.Sizer, its total size. Otherwise 0 to report unknown size]]
           }
        }

        @property timeout_inactivity {
            [[Terminates the copier with ETIMEDOUT if it becomes inactive for some time.

              If the copier cannot do any read or write in the given
              amount of seconds, then the copier will emit "error"
              event with ETIMEDOUT value.

              This is specified in seconds and is only active for
              greater-than zero. Defaults to inactive.
            ]]
            values {
                seconds: double; [[Number inactive seconds to timeout this copier. If zero or less, it will be disabled.]]
            }
        }

        @property done {
            [[Reports if copier is done.

              A copier is done if source reached "eos" and all data
              was written to "destination".

              The copier is also done when it's @Efl.Io.Closer.closed.
            ]]
            get { }
            set @protected { }
            values {
                done: bool; [[If $true, source is "eos" and all data was written to "destination". If $false, it's still pending some more copies]]
            }
        }

        binbuf_steal {
           [[Steals the internal binbuf and return it to caller.

             The buffer is then owned by caller, which should call
             eina_binbuf_free() when it's done.

             Usually call this method when no @.destination is set, in
             this case you should wait for "done", "data" or "line"
             events and then call it to retrieve (and own!) the data.
           ]]
           return: ptr(Eina.Binbuf) @owned @warn_unused; [[Binbuf]]
        }

        @property pending_size {
            [[Returns the size of the pending buffer.

              The pending buffer is an intermediate buffer where data
              is read from @.source before it's written to
              @.destination, if any.

              This is the equivalent of the size of returned by
              @.binbuf_steal, however it doesn't steal or modify the
              buffer at all, just query its internal size.
            ]]
            get { }
            values {
                size: size; [[The pending buffer size, in bytes.]]
            }
        }

        flush {
            [[Forces reading from source and writing to destination.

              This executes a single read->write cycle, if more data
              could be read from source (ie: not EOS) or not all data
              was written to destination, then $false is
              returned. Then to forcefully drain source and write all
              contents to destination, use in a loop until it returns
              $true.

              The return value matches "done" event, that is, when
              $true is returned, the "done" event is emitted.

              This function may also emit "progress" and "error"
              events.

              \@note this function may block the main loop execution
              until operations complete! This is bad for usability, as
              user interface or other operations may freeze. A better
              approach is to operate asynchronously and wait for
              "done" event.
            ]]
            params {
                may_block: bool; [[If $true, then @Efl.Io.Reader.can_read and @Efl.Io.Writer.can_write are not checked and the call may block.]]
                ignore_line_delimiter: bool; [[Forces flush ignoring line delimiters]]
            }
            return: bool(true); [[$true on success, $false otherwise]]
        }
    }

    events {
        done; [[All available data was copied from source to destination]]
        error: Eina.Error; [[An error happened and the copy stopped]]
        progress; [[Total size changed or Data was read/written]]
        data: ptr(const(Eina.Slice)); [[When data is read to internal buffer, it's emitted in this event. The memory is only valid during event callback dispatched and should not be modified.]]
        line: ptr(const(Eina.Slice)); [[If @.line_delimiter is set, will be emitted with current line. The memory is only valid during event callback dispatched and should not be modified.]]
    }

    implements {
       Efl.Object.constructor;
       Efl.Object.destructor;
       Efl.Object.finalize;
       Efl.Io.Closer.close;
       Efl.Io.Closer.closed { get; }
       Efl.Io.Closer.close_on_exec { get; set; }
       Efl.Io.Closer.close_on_destructor { get; set; }
    }
}