ipcqueue

https://pythonhosted.org/ipcqueue
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ipcqueue is a Python package that provides POSIX and SYS V message queues for exchanging data among...
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### POSIX Message Queue Example

Source: https://pythonhosted.org/ipcqueue

Demonstrates creating, putting messages with priorities, getting messages, and cleaning up a POSIX message queue. Ensure the queue name starts with '/'.

```python
>>> from ipcqueue import posixmq
>>> q = posixmq.Queue('/foo')
>>> q.qsize()
0
>>> q.put([1, 'A'])
>>> q.put([2, 'B'], priority=2)
>>> q.put([3, 'C'], priority=0)
>>> q.qsize()
3
>>> q.get()
[2, 'B']
>>> q.get()
[1, 'A']
>>> q.get()
[3, 'C']
>>> q.close()
>>> q.unlink()

```

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

### POSIX Message Queue Operations

Source: https://pythonhosted.org/ipcqueue/_sources/index.rst.txt

Demonstrates creating, putting messages with priorities, getting messages, and cleaning up a POSIX message queue. Ensure the queue path is valid and accessible.

```python
from ipcqueue import posixmq
q = posixmq.Queue('/foo')
q.qsize()
0
q.put([1, 'A'])
q.put([2, 'B'], priority=2)
q.put([3, 'C'], priority=0)
q.qsize()
3
q.get()
[2, 'B']
q.get()
[1, 'A']
q.get()
[3, 'C']
q.close()
q.unlink()
```

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

### Queue.get_nowait()

Source: https://pythonhosted.org/ipcqueue

Get and return an item from queue, equivalent to `get(block=False)`.

```APIDOC
get_nowait(_msg_type=0_)

Get and return an item from queue, equivalent to `get(block=False)`. _msg_type_ specifies the type of requested message. If it’s `0`, then the first message in the queue is read, if it’s greater than `0`, then the first message in the queue of requested type is read and if it’s less than `0`, then the first message in the queue with the lowest type less than or equal to the absolute value of _msg_type_ will be read.
```

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

### Basic SYS V Message Queue Operations

Source: https://pythonhosted.org/ipcqueue

Demonstrates the basic usage of the `ipcqueue.sysvmq.Queue` class, including creating a queue, putting items with and without specific message types, checking the queue size, retrieving items, and closing the queue.

```python
>>> from ipcqueue import sysvmq
>>> q = sysvmq.Queue(1)
>>> q.qsize()
>>> q.put([1, 'A'])
>>> q.put([2, 'B'], msg_type=2)
>>> q.put([3, 'C'], msg_type=2)
>>> q.put([4, 'D'], msg_type=1)
>>> q.qsize()
4
>>> q.get(msg_type=2)
[2, 'B']
>>> q.get()
[1, 'A']
>>> q.get()
[3, 'C']
>>> q.get()
[4, 'D']
>>> q.close()
```

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

### Queue.qsize()

Source: https://pythonhosted.org/ipcqueue

Return the approximate size of the queue.

```APIDOC
qsize()

Return the approximate size of the queue. Note, `qsize() > 0` doesn’t guarantee that a subsequent `get()` will not block.
```

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

### Queue.qattr()

Source: https://pythonhosted.org/ipcqueue

Return attributes of the message queue.

```APIDOC
qattr()

Return attributes of the message queue as a `dict`: `{'size': 3, 'max_bytes': 8192}`.
```

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

### SYS V Message Queue Operations

Source: https://pythonhosted.org/ipcqueue/_sources/index.rst.txt

Illustrates the usage of SYS V message queues, including creating a queue, putting messages with types, retrieving messages by type or in FIFO order, and closing the queue. Note that SYS V queues use integer IDs.

```python
from ipcqueue import sysvmq
q = sysvmq.Queue(1)
q.qsize()
q.put([1, 'A'])
q.put([2, 'B'], msg_type=2)
q.put([3, 'C'], msg_type=2)
q.put([4, 'D'], msg_type=1)
q.qsize()
4
q.get(msg_type=2)
[2, 'B']
q.get()
[1, 'A']
q.get()
[3, 'C']
q.get()
[4, 'D']
q.close()
```

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

### Queue.get()

Source: https://pythonhosted.org/ipcqueue

Remove and return an item from the queue.

```APIDOC
get(_block=True_, _msg_type=0_)

Remove and return an item from the queue. If _block_ argument is `True`, block if necessary until an item is available. Otherwise, return an item if one is immediately available, else raise the `queue.Empty` exception. _msg_type_ specifies the type of requested message. If it’s `0`, then the first message in the queue is read, if it’s greater than `0`, then the first message in the queue of requested type is read and if it’s less than `0`, then the first message in the queue with the lowest type less than or equal to the absolute value of _msg_type_ will be read.
```

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

### Queue Class

Source: https://pythonhosted.org/ipcqueue

Represents a SYS V message queue.

```APIDOC
class ipcqueue.sysvmq.Queue(_key=None_, _max_bytes=None_)

SYS V message queue.
Constructor for message queue. _key_ is an unique identifier of the queue, must be positive number or `0` for private queue. _max_bytes_ is a maximum number of bytes allowed in queue (maximum value depends on hard system limit).
```

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

### Queue.put()

Source: https://pythonhosted.org/ipcqueue

Put _item_ into the queue.

```APIDOC
put(_item_, _block=True_, _msg_type=1_, _pickle_protocol=1_)

Put _item_ into the queue. If _block_ is `True`, block if necessary until a free slot is available. Otherwise, put an _item_ on the queue if a free slot is immediately available, else raise the `queue.Full` exception. _msg_type_ must be positive integer value, this value can be used by the receiving process for message selection. _pickle_protocol_ is a format used by Python’s `pickle`.
```

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

### Queue.put_nowait()

Source: https://pythonhosted.org/ipcqueue

Put _item_ into the queue, equivalent to `put(item, block=False)`.

```APIDOC
put_nowait(_item_, _msg_type=1_, _pickle_protocol=1_)

Put _item_ into the queue, equivalent to `put(item, block=False)`. _msg_type_ must be positive integer value, this value can be used by the receiving process for message selection. _pickle_protocol_ is a format used by Python’s `pickle`.
```

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

### ipcqueue.posixmq.QueueError

Source: https://pythonhosted.org/ipcqueue

Custom exception for POSIX queue errors.

```APIDOC
## exception ipcqueue.posixmq.QueueError(errno, msg=None)

### Description
Indicates a Queue error. Contains additional attributes `errno` and `msg`.

### Attributes
- **errno** (int) - System-dependent error code.
- **msg** (str) - Error message.

### Constants
- **QueueError.ERROR**
- **QueueError.INVALID_VALUE**
- **QueueError.NO_PERMISSIONS**
- **QueueError.NO_SYSTEM_RESOURCES**
- **QueueError.INVALID_DESCRIPTOR**
- **QueueError.INTERRUPTED**
- **QueueError.TOO_BIG_MESSAGE**
- **QueueError.TIMEOUT**
- **QueueError.DOES_NOT_EXIST**
```

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

### QueueError

Source: https://pythonhosted.org/ipcqueue

Indicates a Queue error. Contains additional attributes _errno_ and _msg_.

```APIDOC
exception ipcqueue.sysvmq.QueueError(_errno_, _msg=None_)

Indicates Queue error. Contains additional attributes _errno_ and _msg_. Value of the _errno_ is system dependent, do don’t use numeric codes directly, use constants **QueueError.ERROR**, **QueueError.INVALID_VALUE**, **QueueError.NO_PERMISSIONS**, **QueueError.NO_SYSTEM_RESOURCES**, **QueueError.INVALID_DESCRIPTOR**, **QueueError.INTERRUPTED** and **QueueError.TOO_BIG_MESSAGE**.
```

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

### Queue.close()

Source: https://pythonhosted.org/ipcqueue

Close a message queue.

```APIDOC
close()

Close a message queue.
```

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

### ipcqueue.posixmq.Queue

Source: https://pythonhosted.org/ipcqueue

Represents a POSIX message queue for inter-process communication.

```APIDOC
## class ipcqueue.posixmq.Queue(name, maxsize=10, maxmsgsize=1024)

### Description
POSIX message queue implementation. Allows processes to communicate by sending and receiving messages.

### Parameters
#### Path Parameters
- **name** (string) - Required - An unique identifier of the queue, must start with `/`.
- **maxsize** (integer) - Optional - The upperbound limit on the number of items that can be placed in the queue. Defaults to 10.
- **maxmsgsize** (integer) - Optional - The maximum size of a message in bytes. Defaults to 1024.

### Methods
#### close()

Close a message queue.

#### get(block=True, timeout=None)

Remove and return an item from the queue. Supports blocking with optional timeout.

- **block** (boolean) - Optional - If True, block until an item is available. Defaults to True.
- **timeout** (float) - Optional - Maximum time in seconds to block. If None, blocks indefinitely.

#### get_nowait()

Get and return an item from queue, equivalent to `get(block=False)`.

#### put(item, block=True, timeout=None, priority=0, pickle_protocol=1)

Put an item into the queue. Supports blocking with optional timeout and priority.

- **item** (any) - Required - The item to put into the queue. Will be pickled.
- **block** (boolean) - Optional - If True, block until a free slot is available. Defaults to True.
- **timeout** (float) - Optional - Maximum time in seconds to block. If None, blocks indefinitely.
- **priority** (integer) - Optional - Priority of the message. Higher values are retrieved first. Defaults to 0.
- **pickle_protocol** (integer) - Optional - The pickle protocol version to use. Defaults to 1.

#### put_nowait(item, priority=0, pickle_protocol=1)

Put an item into the queue without blocking, equivalent to `put(item, block=False)`.

- **item** (any) - Required - The item to put into the queue. Will be pickled.
- **priority** (integer) - Optional - Priority of the message. Higher values are retrieved first. Defaults to 0.
- **pickle_protocol** (integer) - Optional - The pickle protocol version to use. Defaults to 1.

#### qattr()

Return attributes of the message queue as a dictionary.

#### qsize()

Return the approximate size of the queue.

#### unlink()

Remove a message queue. This is an instance method.

### Example
```python
from ipcqueue import posixmq

# Create a queue
q = posixmq.Queue('/my_ipc_queue', maxsize=100)

# Put an item with priority
q.put('hello', priority=5)

# Get an item
message = q.get()
print(message)

# Close and unlink the queue
q.close()
q.unlink()
```
```

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

### ipcqueue.posixmq.unlink

Source: https://pythonhosted.org/ipcqueue

Removes a message queue by its name. This is a class method.

```APIDOC
## unlink(name)

### Description
Remove a message queue by its unique name.

### Parameters
#### Path Parameters
- **name** (string) - Required - The unique name of the message queue to remove. Must start with '/'.

### Request Example
```python
from ipcqueue import posixmq

posixmq.unlink('/my_queue')
```
```
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