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lib/new_relic/util/attr_store.ex

defmodule NewRelic.Util.AttrStore do
# This is an abstraction around ETS that lets us store efficently
# store and access arbitrary key->value pairs for all Transactions we are tracking
#
# It is backed by two ETS tables:
# 1) tracking all processes involved in a Transaction
# 2) collecting attributes stored on a Transaction
@moduledoc false
@ets_options [:named_table, :duplicate_bag, :public]
def new(table) do
:ets.new(collecting(table), @ets_options ++ [write_concurrency: true])
:ets.new(tracking(table), @ets_options ++ [read_concurrency: true, write_concurrency: true])
end
def track(table, pid) do
insert(
tracking(table),
{{pid, :tracking}, true}
)
end
def link(table, parent, child) do
root = find_root(parent, table)
insert(
tracking(table),
[
{{child, :tracking}, true},
{{child, :child_of}, root},
{{root, :root_of}, child}
]
)
end
def root(table, pid) do
find_root(pid, table)
end
def add(table, pid, attrs) when is_list(attrs) do
insert(
collecting(table),
Enum.map(attrs, fn {key, value} -> {pid, {key, value}} end)
)
end
def incr(table, pid, attrs) when is_list(attrs) do
insert(
collecting(table),
Enum.map(attrs, fn {key, value} -> {pid, {key, {:counter, value}}} end)
)
end
def tracking?(table, pid) do
member?(
tracking(table),
{pid, :tracking}
)
end
def collect(table, pid) do
pid
|> with_children(table)
|> find_attributes(table)
|> Enum.reduce(%{}, &collect_attr/2)
end
def untrack(table, pid) do
pid
|> find_root(table)
|> with_children(table)
|> Enum.each(fn pid ->
delete(tracking(table), {pid, :tracking})
end)
end
def purge(table, pid) do
pid
|> find_root(table)
|> with_children(table)
|> Enum.each(fn pid ->
delete(collecting(table), pid)
delete(tracking(table), {pid, :tracking})
delete(tracking(table), {pid, :child_of})
delete(tracking(table), {pid, :root_of})
end)
end
defp find_root(pid, table) do
lookup(
tracking(table),
{pid, :child_of}
)
|> case do
[{_, root} | _] -> root
[] -> pid
end
end
defp with_children(pid, table) do
[pid | find_children(table, pid)]
end
defp find_children(table, root_pid) do
lookup(
tracking(table),
{root_pid, :root_of}
)
|> Enum.map(fn {_, child} -> child end)
end
def find_attributes(pids, table) do
Enum.flat_map(pids, fn pid ->
take(
collecting(table),
pid
)
end)
end
defp collect_attr({_pid, {k, {:list, item}}}, acc), do: Map.update(acc, k, [item], &[item | &1])
defp collect_attr({_pid, {k, {:counter, n}}}, acc), do: Map.update(acc, k, n, &(&1 + n))
defp collect_attr({_pid, {k, v}}, acc), do: Map.put(acc, k, v)
defp collecting(table), do: Module.concat(table, Collecting)
defp tracking(table), do: Module.concat(table, Tracking)
defp lookup(table, term) do
:ets.lookup(table, term)
rescue
ArgumentError -> []
end
defp take(table, term) do
:ets.take(table, term)
rescue
ArgumentError -> []
end
defp insert(table, term) do
:ets.insert(table, term)
rescue
ArgumentError -> false
end
defp delete(table, term) do
:ets.delete(table, term)
rescue
ArgumentError -> false
end
defp member?(table, term) do
:ets.member(table, term)
rescue
ArgumentError -> false
end
end