Struct ReadOptions 

pub struct ReadOptions {

    pub range: BytesRange,
    pub version: Option<String>,
    pub if_match: Option<String>,
    pub if_none_match: Option<String>,
    pub if_modified_since: Option<Timestamp>,
    pub if_unmodified_since: Option<Timestamp>,
    pub content_length_hint: Option<u64>,
    pub concurrent: usize,
    pub chunk: Option<usize>,
    pub gap: Option<usize>,
    pub override_content_type: Option<String>,
    pub override_cache_control: Option<String>,
    pub override_content_disposition: Option<String>,
}

Options for read operations.

Fields

range: BytesRange

Set range for this operation.

If we have a file with size n.

• .. means read bytes in range [0, n) of file.
• 0..1024 and ..1024 means read bytes in range [0, 1024) of file
• 1024.. means read bytes in range [1024, n) of file
• BytesRange::suffix(1024) means read the last min(1024, n) bytes of file

The type implements From<RangeBounds<u64>>, so users can use (1024..).into() instead.

version: Option<String>

Set version for this operation.

This option can be used to retrieve the data of a specified version of the given path.

If the version doesn’t exist, an error with kind crate::ErrorKind::NotFound will be returned.

if_match: Option<String>

Set if_match for this operation.

This option can be used to check if the file’s ETag matches the given ETag.

If file exists and it’s etag doesn’t match, an error with kind crate::ErrorKind::ConditionNotMatch will be returned.

if_none_match: Option<String>

Set if_none_match for this operation.

This option can be used to check if the file’s ETag doesn’t match the given ETag.

If file exists and it’s etag match, an error with kind crate::ErrorKind::ConditionNotMatch will be returned.

if_modified_since: Option<Timestamp>

Set if_modified_since for this operation.

This option can be used to check if the file has been modified since the given timestamp.

If file exists and it hasn’t been modified since the specified time, an error with kind crate::ErrorKind::ConditionNotMatch will be returned.

if_unmodified_since: Option<Timestamp>

Set if_unmodified_since for this operation.

This feature can be used to check if the file hasn’t been modified since the given timestamp.

If file exists and it has been modified since the specified time, an error with kind crate::ErrorKind::ConditionNotMatch will be returned.

content_length_hint: Option<u64>

Known content length of the object.

This is an execution hint that allows OpenDAL to avoid extra metadata requests while planning reads. It must not be used as an object identity or consistency condition.

concurrent: usize

Set concurrent for the operation.

OpenDAL by default to read file without concurrent. This is not efficient for cases when users read large chunks of data. By setting concurrent, opendal will reading files concurrently on support storage services.

By setting concurrent, opendal will fetch chunks concurrently with the give chunk size.

Refer to the performance guide for more details.

chunk: Option<usize>

Set chunk for the operation.

OpenDAL will use services’ preferred chunk size by default. Users can set chunk based on their own needs.

Refer to the performance guide for more details.

gap: Option<usize>

Controls the optimization strategy for range reads in crate::Reader::fetch.

When performing range reads, if the gap between two requested ranges is less than or equal to the configured gap size, OpenDAL will merge these ranges into a single read request and discard the unrequested data in between. This helps reduce the number of API calls to remote storage services.

Set to 0 to disable merging ranges separated by a gap. Overlapping or adjacent ranges are still merged.

This optimization is particularly useful when performing multiple small range reads that are close to each other, as it reduces the overhead of multiple network requests at the cost of transferring some additional data.

Refer to the performance guide for more details.

override_content_type: Option<String>

Specify the content-type header that should be sent back by the operation.

This option is only meaningful when used along with presign.

override_cache_control: Option<String>

Specify the cache-control header that should be sent back by the operation.

This option is only meaningful when used along with presign.

override_content_disposition: Option<String>

Specify the content-disposition header that should be sent back by the operation.

This option is only meaningful when used along with presign.

Trait Implementations

impl Clone for ReadOptions

fn clone(&self) -> ReadOptions

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ReadOptions

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ReadOptions

fn default() -> ReadOptions

Returns the “default value” for a type.

impl Eq for ReadOptions

impl From<ReadOptions> for (BytesRange, OpRead, OpReader)

fn from(value: ReadOptions) -> Self

Converts to this type from the input type.

impl PartialEq for ReadOptions

fn eq(&self, other: &ReadOptions) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for ReadOptions