OCaml Uring

https://ocaml-multicore.github.io/ocaml-uring/
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OCaml Uring is an OCaml package that provides bindings to the Linux io_uring interface for...
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### Get Probe Information with OCaml-uring

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Retrieves probe information for a uring, allowing checks for supported operations.

```ocaml
val get_probe : _ t -> probe
`val get_probe : _ t -> probe`
```

--------------------------------

### Stat File Path with OCaml-uring

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Submits a statx request to get file information. The path is resolved relative to a given file descriptor or the current directory.

```ocaml
val statx :    'a t ->   ?fd:Unix.file_descr ->   mask:Statx.Mask.t ->   string ->   Statx.t ->   Statx.Flags.t ->   'a ->   'a job option
`statx t ?fd ~mask path stat flags` stats `path`, which is resolved relative to `fd` (or the current directory if `fd` is not given).
```

--------------------------------

### Get OCaml-uring SQE Ready Count

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Returns the number of entries in the submission queue ring that are ready to be submitted or have not yet been submitted. This is particularly relevant when using SQPOLL.

```ocaml
val sqe_ready : _ t -> int
```

--------------------------------

### Get OCaml-uring Debug Statistics

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Collects and returns internal metrics about the state of the ouring instance. This function is intended for debugging and performance analysis.

```ocaml
val get_debug_stats : _ t -> Stats.t
```

--------------------------------

### Get OCaml-Uring Queue Depth

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Retrieves the total number of submission slots available for a given Io_uring structure.

```OCaml
val queue_depth : 'a t -> int
```

--------------------------------

### Get OCaml-uring Completion Non-blocking

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Retrieves the next completion entry from the ouring instance without blocking. If no completion is available, it returns `None`. This is useful for polling for results.

```ocaml
val get_cqe_nonblocking : 'a t -> 'a completion_option
```

--------------------------------

### Accept Connection with OCaml-uring

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Submits a request to accept a new connection on a file descriptor. The new file descriptor is configured with SOCK_CLOEXEC, and the remote address is stored.

```ocaml
val accept : 'a t -> Unix.file_descr -> Sockaddr.t -> 'a -> 'a job option
`accept t fd addr d` will submit a request to accept a new connection on `fd`. The new FD will be configured with `SOCK_CLOEXEC`. The remote address will be stored in `addr`.
```

--------------------------------

### OCaml Uring Resolve Flags - Basic Operations

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Resolve/index

Demonstrates basic operations for managing OCaml-uring resolve flags, including creating empty sets, converting from integers, and combining flag sets.

```ocaml
val empty : t
val of_int : int -> t
val (+) : t -> t -> t
```

--------------------------------

### Get File Descriptors from Msghdr in OCaml

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Msghdr/index

Retrieves a list of `Unix.file_descr` associated with a given `msghdr` structure.

```ocaml
val get_fds : t -> Unix.file_descr list
```

--------------------------------

### Ocaml-uring Statx Creation

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/index

Introduces the `create` function for the `Uring.Statx` module. This function is used to create a buffer for statx results, which is then passed to the `statx` system call.

```ocaml
val create : unit -> t
```

--------------------------------

### Fsync File with OCaml-uring

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Submits an fsync(2) request to synchronize file data and metadata to disk. Supports optional offset and length to specify a subset of the file.

```ocaml
val fsync :    'a t ->   ?off:int64 ->   ?len:int ->   Unix.file_descr ->   'a ->   'a job option
`fsync t ?off ?len fd d` will submit an `fsync(2)` request, with the optional offset `off` and length `len` specifying the subset of the file to perform the synchronisation on.
```

--------------------------------

### Connect Socket with OCaml-uring

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Submits a request to connect a file descriptor to a socket address.

```ocaml
val connect : 'a t -> Unix.file_descr -> Unix.sockaddr -> 'a -> 'a job option
`connect t fd addr d` will submit a request to connect `fd` to `addr`.
```

--------------------------------

### Fdatasync File with OCaml-uring

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Submits an fdatasync(2) request to synchronize file data to disk. Supports optional offset and length to specify a subset of the file.

```ocaml
val fdatasync :    'a t ->   ?off:int64 ->   ?len:int ->   Unix.file_descr ->   'a ->   'a job option
`fdatasync t ?off ?len fd d` will submit an `fdatasync(2)` request, with the optional offset `off` and length `len` specifying the subset of the file to perform the synchronisation on.
```

--------------------------------

### Get OCaml-Uring Fixed Buffer

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Retrieves the fixed internal memory buffer associated with an Io_uring structure. Returns a zero-length buffer if no fixed buffer has been set.

```OCaml
val buf : 'a t -> Cstruct.buffer
```

--------------------------------

### Ocaml-uring Op: Network Operations

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Op/index

Defines types for network operations such as `sendmsg`, `recvmsg`, `accept`, `connect`, `send`, `recv`, and `shutdown`.

```ocaml
val sendmsg : t
```

```ocaml
val recvmsg : t
```

```ocaml
val accept : t
```

```ocaml
val connect : t
```

```ocaml
val send : t
```

```ocaml
val recv : t
```

```ocaml
val shutdown : t
```

--------------------------------

### Get Available Chunks in OCaml-Uring Region

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Region/index

Returns the number of free memory chunks currently available in the region. This indicates how many more allocations can be made.

```ocaml
val avail : t -> int
```

--------------------------------

### Create OCaml-Uring Instance

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Creates a new Io_uring structure with a specified queue depth. Optionally configures polling mode with a timeout, which requires privileges. The created structure can be used for submitting I/O operations.

```OCaml
val create : ?polling_timeout:int -> queue_depth:int -> unit -> 'a t
```

--------------------------------

### Get Active OCaml-uring Operations

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Returns the count of operations that have been added to the ring but whose completion events have not yet been collected. This metric helps in understanding the current workload.

```ocaml
val active_ops : _ t -> int
```

--------------------------------

### Ocaml-uring Open Flags: Creat

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Open_flags/index

The `creat` flag specifies that if the target pathname does not exist, it should be created as a regular file. This is a common flag for file creation during open operations.

```ocaml
val creat : t
```

--------------------------------

### Initialize OCaml-Uring Region

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Region/index

Initializes a memory region for OCaml-Uring operations. It takes a block size, a buffer, and the number of slots to create the region.

```ocaml
val init : block_size:int -> Cstruct.buffer -> int -> t
```

--------------------------------

### Get Chunk Length in OCaml-Uring Region

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Region/index

Retrieves the block size (length) of a given memory chunk. This is useful for understanding the size of the allocated memory segment.

```ocaml
val length : chunk -> int
```

--------------------------------

### Read from File Descriptor with OCaml-uring

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Submits a read(2) request to a uring. Reads bytes from a file descriptor at a specific offset and writes to a memory buffer. The user data is returned upon completion.

```ocaml
val read :    ?len:int ->   'a t ->   file_offset:offset ->   Unix.file_descr ->   off:int ->   'a ->   'a job option
`read t ~file_offset fd ~off ~len d` will submit a `read(2)` request to uring `t`. It reads up to `len` bytes from absolute `file_offset` on the `fd` file descriptor and writes the results into the fixed memory buffer associated with uring `t` at offset `off`. The user data `d` will be returned by `wait` or `peek` upon completion.
```

--------------------------------

### Statx Flags: Force Sync Behavior in OCaml

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/Flags/index

Explains the `statx_force_sync` flag, which compels synchronization with the server, particularly relevant for network-backed filesystems.

```ocaml
val statx_force_sync : t
(* statx_force_sync forces synchronisation with the server, if the filesystem is a network-backed one. *)
```

--------------------------------

### Ocaml-uring Statx Kind Formatting

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/index

Provides a function `pp_kind` to format the `kind` type into a human-readable string. This is useful for displaying file types in a user-friendly manner.

```ocaml
val pp_kind : kind Fmt.t
```

--------------------------------

### Ocaml-uring openat2 Function

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Opens a file path with specified access modes, flags, permissions, and path resolution options. It supports resolving paths relative to a given file descriptor. The function returns a job that completes with the opened file descriptor.

```ocaml
val openat2 :    'a t ->   access:[ `R | `W | `RW ] ->   flags:Open_flags.t ->   perm:Unix.file_perm ->   resolve:Resolve.t ->   ?fd:Unix.file_descr ->   string ->   'a ->   'a job option
```

--------------------------------

### Ocaml-uring Op: File System Operations

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Op/index

Defines types for various file system operations such as `fsync`, `files_update`, `statx`, `fadvise`, `madvise`, `openat`, `close`, `openat2`, `fallocate`, `renameat`, `unlinkat`, `mkdirat`, `symlinkat`, `linkat`, and `fsetxattr`, `setxattr`, `fgetxattr`, `getxattr`.

```ocaml
val fsync : t
```

```ocaml
val files_update : t
```

```ocaml
val statx : t
```

```ocaml
val fadvise : t
```

```ocaml
val madvise : t
```

```ocaml
val openat : t
```

```ocaml
val close : t
```

```ocaml
val openat2 : t
```

```ocaml
val fallocate : t
```

```ocaml
val renameat : t
```

```ocaml
val unlinkat : t
```

```ocaml
val mkdirat : t
```

```ocaml
val symlinkat : t
```

```ocaml
val linkat : t
```

```ocaml
val fsetxattr : t
```

```ocaml
val setxattr : t
```

```ocaml
val fgetxattr : t
```

```ocaml
val getxattr : t
```

--------------------------------

### OCaml-uring Private.Heap: create function

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Private/Heap/index

The `create n` function initializes a new heap that can hold at most `n` elements. This function is essential for setting up the heap data structure.

```ocaml
val create : int -> _ t
```

--------------------------------

### Send Message with OCaml-uring

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Submits a sendmsg(2) request. Constructs the Msghdr from file descriptors, address, and buffers. Requires the number of buffers to be within the iov_max limit.

```ocaml
val send_msg :    ?fds:Unix.file_descr list ->   ?dst:Unix.sockaddr ->   'a t ->   Unix.file_descr ->   Cstruct.t list ->   'a ->   'a job option
`send_msg t fd buffs d` will submit a `sendmsg(2)` request. The `Msghdr` will be constructed from the FDs (`fds`), address (`dst`) and buffers (`buffs`).
Requires `List.length buffs <= Uring.iov_max`
  * parameter dst
Destination address.


  * parameter fds
Extra file descriptors to attach to the message.
```

--------------------------------

### Ocaml-uring Open Flags: Excl

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Open_flags/index

The `excl` flag, used with `creat`, ensures that the file is created exclusively by the `openat2` call. If the file already exists, the operation fails with `Unix.EEXIST`. It can also be used with block devices to fail if they are already mounted (`Unix.EBUSY`).

```ocaml
val excl : t
```

--------------------------------

### Write to File Descriptor with OCaml-uring

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Submits a write(2) request to a uring. Writes bytes from a memory buffer to a file descriptor at a specific offset. The user data is returned upon completion.

```ocaml
val write_fixed :    'a t ->   file_offset:offset ->   Unix.file_descr ->   off:int ->   len:int ->   'a ->   'a job option
`write t ~file_offset fd off d` will submit a `write(2)` request to uring `t`. It writes up to `len` bytes into absolute `file_offset` on the `fd` file descriptor from the fixed memory buffer associated with uring `t` at offset `off`. The user data `d` will be returned by `wait` or `peek` upon completion.
```

--------------------------------

### Ocaml-uring Op: Miscellaneous Operations

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Op/index

Defines types for various other operations like `sync_file_range`, `timeout_remove`, `async_cancel`, `splice`, `tee`, `provide_buffers`, `remove_buffers`, `uring_cmd`, `msg_ring`, `epoll_ctl`, and `socket`.

```ocaml
val sync_file_range : t
```

```ocaml
val timeout_remove : t
```

```ocaml
val async_cancel : t
```

```ocaml
val splice : t
```

```ocaml
val tee : t
```

```ocaml
val provide_buffers : t
```

```ocaml
val remove_buffers : t
```

```ocaml
val uring_cmd : t
```

```ocaml
val msg_ring : t
```

```ocaml
val epoll_ctl : t
```

```ocaml
val socket : t
```

--------------------------------

### Ocaml-uring linkat Function

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Creates a new hard link to an existing file. It allows specifying paths relative to different directory file descriptors and provides flags to control the linking behavior. If the target path already exists, it is not overwritten.

```ocaml
val linkat :    'a t ->   ?old_dir_fd:Unix.file_descr ->   ?new_dir_fd:Unix.file_descr ->   flags:Linkat_flags.t ->   old_path:string ->   new_path:string ->   'a ->   'a job option
```

--------------------------------

### Ocaml-uring Timeout Function

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Submits a timeout request to the io_uring interface. It allows specifying a clock source (Boottime or Realtime) and a timeout duration in nanoseconds. The `absolute` flag determines how the clock and nanosecond values relate.

```ocaml
type clock = 
  | Boottime
  | Realtime

val timeout : ?absolute:bool -> 'a t -> clock -> int64 -> 'a -> 'a job option
```

--------------------------------

### Submit OCaml-uring Operations

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Submits all outstanding queued requests on an ouring instance to the kernel. Results can be retrieved using `wait` or `peek`. This function is fundamental for initiating asynchronous operations.

```ocaml
val submit : 'a t -> int
```

--------------------------------

### Statx Flags: Sync As Stat Behavior in OCaml

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/Flags/index

Describes the `statx_sync_as_stat` flag, which defines the filesystem-specific behavior when responding to `stat` calls.

```ocaml
val statx_sync_as_stat : t
(* statx_sync_as_stat is the filesystem-specific behaviour in response to stat calls. *)
```

--------------------------------

### OCaml Uring Resolve Flags - InRoot

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Resolve/index

Details the `in_root` flag for OCaml-uring resolve, which treats a specified directory as the root for path resolution.

```ocaml
val in_root : t
```

--------------------------------

### Receive Message with OCaml-uring

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Submits a recvmsg(2) request. If successful, the Msghdr will contain the sender address and received data.

```ocaml
val recv_msg : 'a t -> Unix.file_descr -> Msghdr.t -> 'a -> 'a job option
`recv_msg t fd msghdr d` will submit a `recvmsg(2)` request. If the request is successful then the `msghdr` will contain the sender address and the data received.
```

--------------------------------

### Check Operation Support with OCaml-uring

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Checks if a specific operation is supported by the kernel using probe information.

```ocaml
val op_supported : probe -> Op.t -> bool
`val op_supported : probe -> Op.t -> bool`
```

--------------------------------

### Submit No-Operation to OCaml-Uring

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Submits a no-operation (noop) operation to the specified Io_uring structure. The provided user data `d` will be returned upon completion. Returns None if the submission fails due to a full ring.

```OCaml
val noop : 'a t -> 'a -> 'a job option
```

--------------------------------

### Ocaml-uring Open Flags: Path

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Open_flags/index

The `path` flag obtains a file descriptor that can only be used to indicate a location in the filesystem tree or perform fd-level operations. The file itself is not opened, and I/O operations will fail. It's primarily used with `cloexec`, `directory`, and `nofollow`.

```ocaml
val path : t
```

--------------------------------

### Close File Descriptor with OCaml-uring

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Submits a request to close a file descriptor.

```ocaml
val close : 'a t -> Unix.file_descr -> 'a -> 'a job option
```

--------------------------------

### OCaml Uring Resolve Flags - Beneath

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Resolve/index

Explains the `beneath` flag for OCaml-uring resolve, which restricts path resolution to descendants of a specified directory.

```ocaml
val beneath : t
```

--------------------------------

### Register Eventfd with OCaml-uring

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Registers an eventfd with the ouring instance. This allows the eventfd to be used for signaling completion events. Refer to the io_uring_register_eventfd documentation for details.

```ocaml
val register_eventfd : 'a t -> Unix.file_descr -> unit
```

--------------------------------

### Ocaml-uring Statx Block Size

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/index

Provides a function `blksize` to retrieve the block size of the filesystem for a given statx result. This is typically returned as a 64-bit integer.

```ocaml
val blksize : t -> Stdlib.Int64.t
```

--------------------------------

### Create Msghdr in OCaml

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Msghdr/index

Creates a new `msghdr` structure using provided buffers for `iovec`. It supports optional remote address and the number of file descriptors to reserve for receiving data. Requires the number of buffers to be less than or equal to `Uring.iov_max`.

```ocaml
val create : ?n_fds:int -> ?addr:Sockaddr.t -> Cstruct.t list -> t
```

--------------------------------

### Ocaml-uring Op: Timer Operations

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Op/index

Defines types for timer operations, including `timeout` to set a timeout and `link_timeout` to link a timeout to another operation.

```ocaml
val timeout : t
```

```ocaml
val link_timeout : t
```

--------------------------------

### Ocaml-uring Statx Kind Enumeration

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/index

Defines the `kind` type for the `Uring.Statx` module, enumerating different types of file system objects such as regular files, directories, symbolic links, and more. This type is used to represent the type of a file or directory retrieved via the statx system call.

```ocaml
type kind = [
  | `Unknown
  | `Fifo
  | `Character_special
  | `Directory
  | `Block_device
  | `Regular_file
  | `Symbolic_link
  | `Socket
]
```

--------------------------------

### Ocaml-uring Statx Access Time (Seconds)

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/index

Provides a function `atime_sec` to retrieve the seconds part of the last access time of the file from a statx result. This is returned as a 64-bit integer.

```ocaml
val atime_sec : t -> int64
```

--------------------------------

### Ocaml-uring Open Flags: Sync

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Open_flags/index

The `sync` flag ensures that write operations on the file complete according to the requirements of synchronized I/O file integrity completion. This guarantees that all data and metadata are written to stable storage.

```ocaml
val sync : t
```

--------------------------------

### Exit OCaml-Uring Instance

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Shuts down an Io_uring structure. Any subsequent requests to this structure will fail. Raises Invalid_argument if there are any operations still in progress.

```OCaml
val exit : 'a t -> unit
```

--------------------------------

### Ocaml-uring Statx Direct I/O Offset Alignment

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/index

Provides a function `dio_offset_align` to retrieve the offset alignment requirement for Direct I/O operations from a statx result. This is returned as a 64-bit integer. Refer to `Mask.dioalign` for more details.

```ocaml
val dio_offset_align : t -> Stdlib.Int64.t
```

--------------------------------

### Ocaml-uring Statx Birth Time (Seconds)

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/index

Provides a function `btime_sec` to retrieve the seconds part of the birth time (creation time) of the file from a statx result. This is returned as a 64-bit integer.

```ocaml
val btime_sec : t -> int64
```

--------------------------------

### Ocaml-uring writev Function

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Performs a scatter-gather write operation on a file descriptor. It writes data from a list of buffers to a specified absolute file offset. The number of buffers is limited by `Uring.iov_max`. The operation is submitted to io_uring.

```ocaml
val writev :    'a t ->   file_offset:offset ->   Unix.file_descr ->   Cstruct.t list ->   'a ->   'a job option
```

--------------------------------

### Wait for OCaml-uring Completions

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Blocks until an outstanding event completes on the ouring instance, or until a specified timeout occurs. It automatically calls `submit` and returns the result or `None` if no completion occurred. The result includes user data and the syscall result.

```ocaml
val wait : ?timeout:float -> 'a t -> 'a completion_option
```

--------------------------------

### Ocaml-uring write Function

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Performs a write operation on a file descriptor. It writes data from a provided buffer to a specified absolute file offset. The operation is submitted to the io_uring interface and returns user data upon completion.

```ocaml
val write :    'a t ->   file_offset:offset ->   Unix.file_descr ->   Cstruct.t ->   'a ->   'a job option
```

--------------------------------

### Ocaml-uring Statx Direct I/O Memory Alignment

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/index

Provides a function `dio_mem_align` to retrieve the memory alignment requirement for Direct I/O operations from a statx result. This is returned as a 64-bit integer. Refer to `Mask.dioalign` for more details.

```ocaml
val dio_mem_align : t -> Stdlib.Int64.t
```

--------------------------------

### Statx Flags: Empty Path Behavior in OCaml

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/Flags/index

Documents the `empty_path` flag for the `statx` system call. When set, it specifies that if the pathname is empty, the operation should apply to the file referred to by the `fd`. If `fd` is not provided, it defaults to the current working directory.

```ocaml
val empty_path : t
(* empty_path signals that if the pathname is an empty string then operate on the file referred to by the `fd` (which can refer to any type of file). If `fd` is not specified then the call operates on the current working directory. *)
```

--------------------------------

### Ocaml-uring Op: Write Operations

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Op/index

Defines types for write operations, including `writev` for scatter-gather writes and `write_fixed` for fixed-size buffer writes.

```ocaml
val writev : t
```

```ocaml
val write_fixed : t
```

```ocaml
val write : t
```

--------------------------------

### Ocaml-uring Op: Read Operations

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Op/index

Defines types for read operations, including `readv` for scatter-gather reads and `read_fixed` for fixed-size buffer reads.

```ocaml
val readv : t
```

```ocaml
val read_fixed : t
```

```ocaml
val read : t
```

--------------------------------

### Ocaml-uring Statx Number of Links

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/index

Provides a function `nlink` to retrieve the number of hard links to the file from a statx result. This value is returned as a 64-bit integer.

```ocaml
val nlink : t -> Stdlib.Int64.t
```

--------------------------------

### Ocaml-uring read Function

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Performs a read operation on a file descriptor. It reads data from a specified absolute file offset into a provided buffer. The operation is submitted to the io_uring interface and returns user data upon completion.

```ocaml
type offset := Optint.Int63.t

val read :    'a t ->   file_offset:offset ->   Unix.file_descr ->   Cstruct.t ->   'a ->   'a job option
```

--------------------------------

### Ocaml-uring Open Flags: Nofollow

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Open_flags/index

The `nofollow` flag causes the open operation to fail with `Unix.ELOOP` if the basename of the path is a symbolic link. This prevents following symbolic links during path resolution.

```ocaml
val nofollow : t
```

--------------------------------

### OCaml Uring Resolve Flags - Cached

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Resolve/index

Describes the `cached` flag for OCaml-uring resolve, which makes the open operation fail if path components are not in the kernel lookup cache.

```ocaml
val cached : t
```

--------------------------------

### Ocaml-uring readv Function

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/index

Performs a scatter-gather read operation on a file descriptor. It reads data from a specified absolute file offset into a list of buffers. The number of buffers is limited by `Uring.iov_max`. The operation is submitted to io_uring.

```ocaml
val readv :    'a t ->   file_offset:offset ->   Unix.file_descr ->   Cstruct.t list ->   'a ->   'a job option
```

--------------------------------

### Ocaml-uring Open Flags: Direct I/O

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Open_flags/index

The `direct` flag bypasses the kernel's buffer cache, performing I/O directly between userspace buffers and the storage device. This can improve performance for certain workloads but requires careful management.

```ocaml
val direct : t
```

--------------------------------

### Ocaml-uring Statx.Attr Flags

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/Attr/index

Defines the `t` type for file attribute flags and provides basic operations like union and membership testing.

```ocaml
module Statx : sig
  module Attr : sig
    include FLAGS
    type t = private int
    val empty : t
    val of_int : int -> t
    val (+) : t -> t -> t
    val mem : t -> t -> bool
    val compressed : t
    val immutable : t
    val append : t
    val nodump : t
    val encrypted : t
    val verity : t
    val dax : t
    val check : ?mask:Stdlib.Int64.t -> Stdlib.Int64.t -> t -> bool
  end
end
```

--------------------------------

### Ocaml-uring Statx Device ID (dev)

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/index

Provides a function `dev` to retrieve the device ID of the filesystem containing the file from a statx result. This is returned as a 64-bit integer.

```ocaml
val dev : t -> Stdlib.Int64.t
```

--------------------------------

### OCaml Uring Resolve Flags - NoSymlinks

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Resolve/index

Explains the `no_symlinks` flag for OCaml-uring resolve, which disallows the resolution of all symbolic links and implies `no_magiclinks`.

```ocaml
val no_symlinks : t
```

--------------------------------

### OCaml Uring Resolve Flags - NoXdev

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Resolve/index

Details the `no_xdev` flag for OCaml-uring resolve, which prevents traversal across different mount points during path resolution.

```ocaml
val no_xdev : t
```

--------------------------------

### Convert OCaml-Uring Chunk to Bigarray

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Region/index

Creates a zero-copy view of a memory chunk as a Bigarray. Similar to `to_cstruct`, this provides direct memory access but necessitates careful lifecycle management of the chunk and the Bigarray.

```ocaml
val to_bigstring : ?len:int -> chunk -> Cstruct.buffer
```

--------------------------------

### Ocaml-uring Statx File Size

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/index

Provides a function `size` to retrieve the total size of the file in bytes from a statx result. The size is returned as a 64-bit integer.

```ocaml
val size : t -> Stdlib.Int64.t
```

--------------------------------

### Ocaml-uring Statx Attributes

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/index

Provides a function `attributes` to retrieve the file attributes from a statx result. The attributes are returned as a 64-bit integer.

```ocaml
val attributes : t -> Stdlib.Int64.t
```

--------------------------------

### Ocaml-uring Open Flags: Cloexec

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Open_flags/index

The `cloexec` flag enables the close-on-exec flag for the newly created file descriptor. This means the file descriptor will be automatically closed when an execve system call is made.

```ocaml
val cloexec : t
```

--------------------------------

### Ocaml-uring Open Flags: Directory

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Open_flags/index

The `directory` flag ensures that the open operation only succeeds if the target path refers to a directory. If the target is not a directory, the operation will fail.

```ocaml
val directory : t
```

--------------------------------

### Ocaml-uring Statx Access Time (Nanoseconds)

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/index

Provides a function `atime_nsec` to retrieve the nanoseconds part of the last access time of the file from a statx result. This is returned as an integer.

```ocaml
val atime_nsec : t -> int
```

--------------------------------

### Ocaml-uring Statx Birth Time (Nanoseconds)

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Statx/index

Provides a function `btime_nsec` to retrieve the nanoseconds part of the birth time (creation time) of the file from a statx result. This is returned as an integer.

```ocaml
val btime_nsec : t -> int
```

--------------------------------

### Convert OCaml-Uring Chunk to String

Source: https://ocaml-multicore.github.io/ocaml-uring/uring/Uring/Region/index

Returns a copy of a memory chunk as an OCaml string. This operation involves copying the memory content.

```ocaml
val to_string : ?len:int -> chunk -> string
```
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