Struct BodySink

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pub struct BodySink { /* private fields */ }

Expand description

A logical buffer of bytes, which may or may not be RAM resident, in the process of being written.

This is the write-side corollary to BodyImage. A BodySink is always in one of the following states, as a buffering strategy:

Ram : A vector of zero, one, or many discontinuous (AKA scattered) byte buffers in Random Access Memory. This state is also used to represent an empty body (without allocation).

FsWrite : Body being written to a (temporary) file.

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impl BodySink

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pub fn empty() -> BodySink

Create new empty instance, which does not pre-allocate. The state is Ram with a zero-capacity vector.

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pub fn with_ram(size_estimate: u64) -> BodySink

Create a new Ram instance by pre-allocating a vector of buffers based on the given size estimate in bytes, assuming 8 KiB buffers. With a size_estimate of 0, this is the same as empty.

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pub fn with_ram_buffers(capacity: usize) -> BodySink

Create a new Ram instance by pre-allocating a vector of the specified capacity.

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pub fn with_fs(dir: P) -> Result<BodySink, BodyError>
where P: AsRef<Path>,

Create a new instance in state FsWrite, using a new temporary file created in dir.

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pub fn is_ram(&self) -> bool

Return true if in state Ram.

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pub fn is_empty(&self) -> bool

Return true if body is empty.

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pub fn len(&self) -> u64

Return the current length of body in bytes.

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pub fn save<T>(&mut self, buf: T) -> Result<(), BodyError>
where T: Into<Bytes>,

👎Deprecated since 2.0.0: use push or write_all instead

Push Bytes-convertable buffer to end of Ram vector, or by writing to end of FsWrite file.

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pub fn push<T>(&mut self, buf: T) -> Result<(), Error>
where T: Into<Bytes> + AsRef<[u8]>,

Push Bytes-convertable buffer to end of Ram vector, or by writing to end of FsWrite file.

Note the additional Into<Bytes> bound vs write_all. When in state Ram, push is more efficient than write_all if Into<Bytes> does not copy. When in state FsWrite it is the same.

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pub fn write_all<T>(&mut self, buf: T) -> Result<(), Error>
where T: AsRef<[u8]>,

Write all bytes to end of self.

Prefer push to this method if the additional bound is met. Only when in state FsWrite is this method copy free.

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pub fn write_back(&mut self, dir: P) -> Result<&mut Self, BodyError>
where P: AsRef<Path>,

If Ram, convert to FsWrite by writing all bytes in RAM to a temporary file, created in dir. No-op if already FsWrite. Buffers are eagerly dropped as they are written. As a consequence, if any error result is returned (e.g. opening or writing to the file), self will be empty and in the Ram state. There is no practical recovery for the original body.

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