=================
HTTP Crate Client
=================

Server configuration
====================

A list of servers can be passed while creating an instance of the http client::

    >>> http_client = HttpClient([crate_host])

Its also possible to pass a single server as a string::

    >>> http_client = HttpClient(crate_host)

If no ``server` argument (or no argument at all) is passed, the default one ``127.0.0.1:9200``
is used::

    >>> http_client = HttpClient()
    >>> http_client._active_servers
    ['127.0.0.1:9200']

When using a list of servers, the servers are selected by round-robin::

    >>> invalid_host = "invalid_host:9999"
    >>> even_more_invalid_host = "even_more_invalid_host:9999"
    >>> http_client = HttpClient([crate_host, invalid_host, even_more_invalid_host])
    >>> http_client._get_server()
    '127.0.0.1:9295'

    >>> http_client._get_server()
    'invalid_host:9999'

    >>> http_client._get_server()
    'even_more_invalid_host:9999'

Servers with connection errors will be removed from the active server list::

    >>> http_client = HttpClient([invalid_host, even_more_invalid_host, crate_host])
    >>> result = http_client.sql('select name from locations')
    >>> http_client._active_servers
    ['127.0.0.1:9295']

Inactive servers will be re-added after a given time interval.
To validate this, set the interval very short and sleep for that interval::

    >>> http_client.retry_interval = 1
    >>> import time; time.sleep(1)
    >>> result = http_client.sql('select name from locations')
    >>> http_client._active_servers
    ['invalid_host:9999', 'even_more_invalid_host:9999', '127.0.0.1:9295']

If no active servers are available and the retry interval is not reached, just use the oldest
inactive one::

    >>> http_client = HttpClient([invalid_host, even_more_invalid_host, crate_host])
    >>> result = http_client.sql('select name from locations')
    >>> http_client._active_servers = []
    >>> http_client._get_server()
    'invalid_host:9999'


SQL Statements
==============

Issue a select statement against our with test data pre-filled crate instance::

    >>> http_client = HttpClient(crate_host)
    >>> result = http_client.sql('select name from locations')
    >>> pprint(result)
    {u'cols': [u'name'],
     u'rows': [[u'Algol'],
               [u'Folfanga'],
               [u'Aldebaran'],
               [u'Argabuthon'],
               [u'Bartledan'],
               [u'Galactic Sector QQ7 Active J Gamma'],
               [u'Allosimanius Syneca'],
               [u'Arkintoofle Minor'],
               [u'Outer Eastern Rim'],
               [u'Altair']]}

Blobs
=====

Check if a blob exists::

    >>> http_client.blob_exists('myfiles', '040f06fd774092478d450774f5ba30c5da78acc8')
    False

Trying to get a non-existing blob throws an exception::

    >>> http_client.blob_get('myfiles', '040f06fd774092478d450774f5ba30c5da78acc8')
    Traceback (most recent call last):
    ...
    DigestNotFoundException: myfiles/040f06fd774092478d450774f5ba30c5da78acc8

Creating a new blob - this method returns True if the blob was newly
created, false if it already exists::

    >>> from tempfile import TemporaryFile
    >>> f = TemporaryFile()
    >>> _ = f.write(b'content')
    >>> _ = f.seek(0)
    >>> http_client.blob_put(
    ...     'myfiles', '040f06fd774092478d450774f5ba30c5da78acc8', f)
    True

    >>> _ = f.seek(0)
    >>> http_client.blob_put(
    ...     'myfiles', '040f06fd774092478d450774f5ba30c5da78acc8', f)
    False

The blob should now exist::

    >>> http_client.blob_exists('myfiles', '040f06fd774092478d450774f5ba30c5da78acc8')
    True

Blobs are returned as generators, generating a chunk on each call::

    >>> g = http_client.blob_get('myfiles', '040f06fd774092478d450774f5ba30c5da78acc8')
    >>> print(next(g))
    content

The chunk_size can be set explicitly on get::

    >>> g = http_client.blob_get(
    ...     'myfiles', '040f06fd774092478d450774f5ba30c5da78acc8', 5)
    >>> print(next(g))
    conte

    >>> print(next(g))
    nt

Deleting a blob - this method returns true if the blob existed::

    >>> http_client.blob_del('myfiles', '040f06fd774092478d450774f5ba30c5da78acc8')
    True

    >>> http_client.blob_del('myfiles', '040f06fd774092478d450774f5ba30c5da78acc8')
    False


Error Handling
==============

It's possible to define a HTTP timeout in seconds on client instantiation, so a timeout exception
is raised when timeout is reached::

    >>> http_client = HttpClient(crate_host, timeout=0.001)
    >>> http_client.sql('select name from locations')
    Traceback (most recent call last):
    ...
    ConnectionError: No more Servers available, exception from last server: HTTPConnectionPool(host='...', port=...): Request timed out. (timeout=0.001)
