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|
defmodule Farside do
@service_prefix Application.fetch_env!(:farside, :service_prefix)
@fallback_suffix Application.fetch_env!(:farside, :fallback_suffix)
@previous_suffix Application.fetch_env!(:farside, :previous_suffix)
def get_services_map do
{:ok, service_list} = Redix.command(:redix, ["KEYS", "#{@service_prefix}*"])
# Match service name to list of available instances
Enum.reduce(service_list, %{}, fn service, acc ->
{:ok, instance_list} =
Redix.command(
:redix,
["LRANGE", service, "0", "-1"]
)
Map.put(
acc,
String.replace_prefix(
service,
@service_prefix,
""
),
instance_list
)
end)
end
def pick_instance(service) do
{:ok, instances} =
Redix.command(
:redix,
[
"LRANGE",
"#{@service_prefix}#{service}",
"0",
"-1"
]
)
# Either pick a random available instance,
# or fall back to the default one
instance =
if Enum.count(instances) > 0 do
if Enum.count(instances) == 1 do
# If there's only one instance, just return that one...
List.first(instances)
else
# ...otherwise pick a random one from the list, ensuring
# that the same instance is never picked twice in a row.
{:ok, previous} =
Redix.command(
:redix,
["GET", "#{service}#{@previous_suffix}"]
)
instance =
Enum.filter(instances, &(&1 != previous))
|> Enum.random()
Redix.command(
:redix,
["SET", "#{service}#{@previous_suffix}", instance]
)
instance
end
else
{:ok, result} =
Redix.command(
:redix,
["GET", "#{service}#{@fallback_suffix}"]
)
result
end
instance
end
def get_last_updated do
{:ok, last_updated} =
Redix.command(
:redix,
["GET", "last_updated"]
)
last_updated
end
end
|
