defmodule Amqpx.Basic do
@moduledoc """
Functions to publish, consume and acknowledge messages.
"""
import Amqpx.Core
alias Amqpx.{Channel, Utils}
@type error :: {:error, reason :: :blocked | :closing}
@type exchange :: String.t()
@type queue :: String.t()
@type routing_key :: String.t()
@type payload :: String.t()
@type delivery_tag :: integer
@type consumer_tag :: String.t()
@doc """
Publishes a message to an Exchange.
This method publishes a message to a specific exchange. The message will be routed
to queues as defined by the exchange configuration and distributed to any subscribers.
The parameter `exchange` specifies the name of the exchange to publish to. If set to
empty string, it publishes to the default exchange.
The `routing_key` parameter specifies the routing key for the message.
The `payload` parameter specifies the message content as a binary.
In addition to the previous parameters, the following options can be used:
## Options
* `:mandatory` - If set, returns an error if the broker can't route the message to a queue (default `false`);
* `:immediate` - If set, returns an error if the broker can't deliver the message to a consumer immediately (default `false`);
* `:content_type` - MIME Content type;
* `:content_encoding` - MIME Content encoding;
* `:headers` - Message headers of type `t:Amqpx.arguments/0`. Can be used with headers Exchanges;
* `:persistent` - If set, uses persistent delivery mode. Messages marked as `persistent` that are delivered to `durable` \
queues will be logged to disk;
* `:correlation_id` - application correlation identifier;
* `:priority` - message priority, ranging from 0 to 9;
* `:reply_to` - name of the reply queue;
* `:expiration` - how long the message is valid (in milliseconds);
* `:message_id` - message identifier;
* `:timestamp` - timestamp associated with this message (epoch time);
* `:type` - message type as a string;
* `:user_id` - creating user ID. RabbitMQ will validate this against the active connection user;
* `:app_id` - publishing application ID.
## Examples
iex> Amqpx.Basic.publish chan, \"my_exchange\", \"my_routing_key\", \"Hello World!\", persistent: true
:ok
"""
@spec publish(Channel.t(), exchange, routing_key, payload, keyword) :: :ok | error
def publish(%Channel{pid: pid}, exchange, routing_key, payload, options \\ []) do
basic_publish =
basic_publish(
exchange: exchange,
routing_key: routing_key,
mandatory: Keyword.get(options, :mandatory, false),
immediate: Keyword.get(options, :immediate, false)
)
p_basic =
p_basic(
content_type: Keyword.get(options, :content_type, :undefined),
content_encoding: Keyword.get(options, :content_encoding, :undefined),
headers: options |> Keyword.get(:headers, :undefined) |> Utils.to_type_tuple(),
delivery_mode: if(options[:persistent], do: 2, else: 1),
priority: Keyword.get(options, :priority, :undefined),
correlation_id: Keyword.get(options, :correlation_id, :undefined),
reply_to: Keyword.get(options, :reply_to, :undefined),
expiration: Keyword.get(options, :expiration, :undefined),
message_id: Keyword.get(options, :message_id, :undefined),
timestamp: Keyword.get(options, :timestamp, :undefined),
type: Keyword.get(options, :type, :undefined),
user_id: Keyword.get(options, :user_id, :undefined),
app_id: Keyword.get(options, :app_id, :undefined),
cluster_id: Keyword.get(options, :cluster_id, :undefined)
)
case :amqp_channel.call(pid, basic_publish, amqp_msg(props: p_basic, payload: payload)) do
:ok -> :ok
error -> {:error, error}
end
end
@doc """
Sets the message prefetch count or prefetech size (in bytes).
## Options
* `:prefetch_size` - the prefetch size (in bytes). Defaults to `0`.
* `:prefetch_count` - the prefetch count. Defaults to `0`.
* `:global` - If set, this applies to the entire Connection, otherwise
it applies only to the given Channel. Defaults to `false`.
"""
@spec qos(Channel.t(), keyword) :: :ok | error
def qos(%Channel{pid: pid}, options \\ []) do
basic_qos =
basic_qos(
prefetch_size: Keyword.get(options, :prefetch_size, 0),
prefetch_count: Keyword.get(options, :prefetch_count, 0),
global: Keyword.get(options, :global, false)
)
case :amqp_channel.call(pid, basic_qos) do
basic_qos_ok() -> :ok
error -> {:error, error}
end
end
@doc """
Acknowledges one or more messages.
## Options
* `:multiple` - If set, all messages up to the one specified by `delivery_tag`
are acknowledged. Defaults to `false`.
"""
@spec ack(Channel.t(), delivery_tag, keyword) :: :ok | error
def ack(%Channel{pid: pid}, delivery_tag, options \\ []) do
basic_ack =
basic_ack(
delivery_tag: delivery_tag,
multiple: Keyword.get(options, :multiple, false)
)
case :amqp_channel.call(pid, basic_ack) do
:ok -> :ok
error -> {:error, error}
end
end
@doc """
Rejects (and, optionally, requeues) a message.
## Options
* `:requeue` - If set, the message is requeued by the server, otherwise
it's discarded. Defaults to `true`.
"""
@spec reject(Channel.t(), delivery_tag, keyword) :: :ok | error
def reject(%Channel{pid: pid}, delivery_tag, options \\ []) do
basic_reject =
basic_reject(
delivery_tag: delivery_tag,
requeue: Keyword.get(options, :requeue, true)
)
case :amqp_channel.call(pid, basic_reject) do
:ok -> :ok
error -> {:error, error}
end
end
@doc """
Negative acknowledges of one or more messages.
This is a RabbitMQ specific extension to Amqpx 0.9.1. It is equivalent to `reject/3`, but allows
rejecting multiple messages using the `multiple` option.
## Options
* `:multiple` - If set, all messages up to the one specified by `delivery_tag`
are considered as not acknowledged by the server. Defaults to `false`.
* `:requeue` - If set, the message will be returned to the queue and redelivered
to the next available consumer. Defaults to `true`.
"""
@spec nack(Channel.t(), delivery_tag, keyword) :: :ok | error
def nack(%Channel{pid: pid}, delivery_tag, options \\ []) do
basic_nack =
basic_nack(
delivery_tag: delivery_tag,
multiple: Keyword.get(options, :multiple, false),
requeue: Keyword.get(options, :requeue, true)
)
case :amqp_channel.call(pid, basic_nack) do
:ok -> :ok
error -> {:error, error}
end
end
@doc """
Polls a queue for an existing message.
Returns the tuple `{:empty, meta}` if the queue is empty or the tuple `{:ok, payload, meta}` if at least
one message exists in the queue. The returned `meta` map includes the entry `:message_count` with the
current number of messages in the queue.
Receiving messages by polling a queue is not as as efficient as subscribing a consumer to a queue,
so consideration should be taken when receiving large volumes of messages.
## Options
* `:no_ack` - If set, the broker is told that the received will not send an acknoledgement
of the message. Once the broker believes it has delivered the message, then it's free to
assume that the consuming application has taken responsibility for it. In general, a lot
of applications will not want these semantics, rather, they will want to explicitly
acknowledge the receipt of a message (through `ack/3`). Defaults to `false` (meaning
explicit acks).
"""
@spec get(Channel.t(), queue, keyword) :: {:ok, String.t(), map} | {:empty, map} | error
def get(%Channel{pid: pid}, queue, options \\ []) do
case :amqp_channel.call(
pid,
basic_get(queue: queue, no_ack: Keyword.get(options, :no_ack, false))
) do
{basic_get_ok(
delivery_tag: delivery_tag,
redelivered: redelivered,
exchange: exchange,
routing_key: routing_key,
message_count: message_count
),
amqp_msg(
props:
p_basic(
content_type: content_type,
content_encoding: content_encoding,
headers: headers,
delivery_mode: delivery_mode,
priority: priority,
correlation_id: correlation_id,
reply_to: reply_to,
expiration: expiration,
message_id: message_id,
timestamp: timestamp,
type: type,
user_id: user_id,
app_id: app_id,
cluster_id: cluster_id
),
payload: payload
)} ->
{:ok, payload,
%{
delivery_tag: delivery_tag,
redelivered: redelivered,
exchange: exchange,
routing_key: routing_key,
message_count: message_count,
content_type: content_type,
content_encoding: content_encoding,
headers: headers,
persistent: delivery_mode == 2,
priority: priority,
correlation_id: correlation_id,
reply_to: reply_to,
expiration: expiration,
message_id: message_id,
timestamp: timestamp,
type: type,
user_id: user_id,
app_id: app_id,
cluster_id: cluster_id
}}
basic_get_empty(cluster_id: cluster_id) ->
{:empty, %{cluster_id: cluster_id}}
error ->
{:error, error}
end
end
@doc """
Asks the server to redeliver all unacknowledged messages on a specified channel.
## Options
* `:requeue` - If set, the server will attempt to requeue the message,
potentially delivering it to another subscriber. Otherwise it will be redelivered
to the original recipient. Defaults to `false`.
"""
@spec recover(Channel.t(), keyword) :: :ok | error
def recover(%Channel{pid: pid}, options \\ []) do
basic_recover = basic_recover(requeue: Keyword.get(options, :requeue, false))
case :amqp_channel.call(pid, basic_recover) do
basic_recover_ok() -> :ok
error -> {:error, error}
end
end
@doc """
Registers a queue consumer process. The `pid` of the process can be set using
the `consumer_pid` argument and defaults to the calling process.
The consumer process will receive the following data structures:
* `{:basic_deliver, payload, meta}` - This is sent for each message consumed, where \
`payload` contains the message content and `meta` contains all the metadata set when \
sending with Basic.publish or additional info set by the broker;
* `{:basic_consume_ok, %{consumer_tag: consumer_tag}}` - Sent when the consumer \
process is registered with Basic.consume. The caller receives the same information \
as the return of Basic.consume;
* `{:basic_cancel, %{consumer_tag: consumer_tag, no_wait: no_wait}}` - Sent by the \
broker when the consumer is unexpectedly cancelled (such as after a queue deletion)
* `{:basic_cancel_ok, %{consumer_tag: consumer_tag}}` - Sent to the consumer process after a call to Basic.cancel
## Options
* `:consumer_tag` - Specifies the consumer tag for this consumer (as a string).
This tag is local to the given channel `chan`, so different channels can have
consumers that use the same consumer tag. If the given consumer tag is `""`,
then the server autogenerates the tag. Defaults to `""`.
* `:no_local` - If set, the server won't send messages to the connection
that published them. Defaults to `false`.
* `:no_ack` - If set, the server will not expect message acks from the consumer and
will consider every message that it believes was delivered to the consumer as
acknowledged. Defaults to `false`, meaning that messages need to be acked
explicitly through `ack/3`.
* `:exclusive` - If set, requests exclusive consumer access, meaning that only
this consumer can consume from the given `queue`. Note that the client cannot
have exclusive access to a queue that already has consumers.
* `:no_wait` - If set, the consume operation is asynchronous. Defaults to
`false`.
* `:arguments` - A list of arguments to pass when consuming (of type `t:Amqpx.arguments/0`).
See the README for more information. Defaults to `[]`.
"""
@spec consume(Channel.t(), String.t(), pid(), keyword) :: {:ok, String.t()} | error
def consume(%Channel{} = chan, queue, consumer_pid, options \\ []) do
basic_consume =
basic_consume(
queue: queue,
consumer_tag: Keyword.get(options, :consumer_tag, ""),
no_local: Keyword.get(options, :no_local, false),
no_ack: Keyword.get(options, :no_ack, false),
exclusive: Keyword.get(options, :exclusive, false),
nowait: Keyword.get(options, :no_wait, false),
arguments: Keyword.get(options, :arguments, [])
)
case :amqp_channel.subscribe(chan.pid, basic_consume, consumer_pid) do
basic_consume_ok(consumer_tag: consumer_tag) -> {:ok, consumer_tag}
error -> {:error, error}
end
end
@doc """
Stops the given consumer from consuming.
This method cancels a consumer. This does not affect already delivered messages, but it does
mean the server will not send any more messages for that consumer. The client may receive an
arbitrary number of messages in between sending the cancel method and receiving the reply.
`consumer_tag` identifies the "subscription" to cancel, that is, the subscription of a
consumer to a specific queue. The consumer tag is returned by `consume/4`.
## Options
* `:no_wait` - If set, the cancel operation is asynchronous. Defaults to
`false`.
"""
@spec cancel(Channel.t(), String.t(), keyword) :: {:ok, String.t()} | error
def cancel(%Channel{pid: pid}, consumer_tag, options \\ []) do
basic_cancel = basic_cancel(consumer_tag: consumer_tag, nowait: Keyword.get(options, :no_wait, false))
case :amqp_channel.call(pid, basic_cancel) do
basic_cancel_ok(consumer_tag: consumer_tag) -> {:ok, consumer_tag}
error -> {:error, error}
end
end
@doc """
Registers a handler to deal with returned messages.
The registered process will receive `{:basic_return, payload, meta}` tuples.
"""
@spec return(Channel.t(), pid) :: :ok
def return(%Channel{pid: pid}, return_handler_pid) do
:amqp_channel.register_return_handler(pid, return_handler_pid)
end
@doc """
Removes the return handler, if it exists. Does nothing if there is no
such handler.
"""
@spec cancel_return(Channel.t()) :: :ok
def cancel_return(%Channel{pid: pid}) do
# Currently we don't remove the receiver.
# The receiver will be deleted automatically when channel is closed.
:amqp_channel.unregister_return_handler(pid)
end
end
