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DirectFileStore : add hostname to identify a process #323

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3 changes: 2 additions & 1 deletion lib/prometheus/client/data_stores/direct_file_store.rb
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
require 'fileutils'
require "cgi"
require 'socket'

module Prometheus
module Client
Expand Down Expand Up @@ -188,7 +189,7 @@ def stores_for_metric
end

def process_id
Process.pid
"#{Socket.gethostname}_#{Process.pid}"
end

def aggregate_values(values)
Expand Down
63 changes: 47 additions & 16 deletions spec/prometheus/client/data_stores/direct_file_store_spec.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -88,17 +88,34 @@

context "when process is forked" do
it "opens a new internal store to avoid two processes using the same file" do
allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(12345)
metric_store = subject.for_metric(:metric_name, metric_type: :counter)
metric_store.increment(labels: {}, by: 1)

allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(23456)
metric_store.increment(labels: {}, by: 1)
expect(Dir.glob('/tmp/prometheus_test/*').size).to eq(2)
expect(metric_store.all_values).to eq({} => 2.0)
end
end

context "many processes in different hosts share the same pid" do
it "opens a new internal store to avoid two processes using the same file" do
allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(12345)
metric_store = subject.for_metric(:metric_name, metric_type: :counter)
metric_store.increment(labels: {}, by: 1)

allow(Socket).to receive(:gethostname).and_return("host2")
allow(Process).to receive(:pid).and_return(12345)
metric_store.increment(labels: {}, by: 1)
expect(Dir.glob('/tmp/prometheus_test/*').size).to eq(2)
expect(metric_store.all_values).to eq({} => 2.0)
end
end

it "coalesces values irrespective of the order of labels" do
metric_store1 = subject.for_metric(:metric_name, metric_type: :counter)
metric_store1.increment(labels: { foo: "1", bar: "1" }, by: 1)
Expand All @@ -117,12 +134,14 @@

context "for a non-gauge metric" do
it "sums values from different processes by default" do
allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(12345)
metric_store1 = subject.for_metric(:metric_name, metric_type: :counter)
metric_store1.set(labels: { foo: "bar" }, val: 1)
metric_store1.set(labels: { foo: "baz" }, val: 7)
metric_store1.set(labels: { foo: "yyy" }, val: 3)

allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(23456)
metric_store2 = subject.for_metric(:metric_name, metric_type: :counter)
metric_store2.set(labels: { foo: "bar" }, val: 3)
Expand All @@ -143,6 +162,7 @@

context "for a gauge metric" do
it "exposes each process's individual value by default" do
allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(12345)
metric_store1 = subject.for_metric(
:metric_name,
Expand All @@ -152,6 +172,7 @@
metric_store1.set(labels: { foo: "baz" }, val: 7)
metric_store1.set(labels: { foo: "yyy" }, val: 3)

allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(23456)
metric_store2 = subject.for_metric(
:metric_name,
Expand All @@ -162,19 +183,20 @@
metric_store2.set(labels: { foo: "zzz" }, val: 1)

expect(metric_store1.all_values).to eq(
{ foo: "bar", pid: "12345" } => 1.0,
{ foo: "bar", pid: "23456" } => 3.0,
{ foo: "baz", pid: "12345" } => 7.0,
{ foo: "baz", pid: "23456" } => 2.0,
{ foo: "yyy", pid: "12345" } => 3.0,
{ foo: "zzz", pid: "23456" } => 1.0,
{ foo: "bar", pid: "host1_12345" } => 1.0,
{ foo: "bar", pid: "host1_23456" } => 3.0,
{ foo: "baz", pid: "host1_12345" } => 7.0,
{ foo: "baz", pid: "host1_23456" } => 2.0,
{ foo: "yyy", pid: "host1_12345" } => 3.0,
{ foo: "zzz", pid: "host1_23456" } => 1.0,
)

# Both processes should return the same value
expect(metric_store1.all_values).to eq(metric_store2.all_values)
end

it "coalesces values irrespective of the order of labels" do
allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(12345)
metric_store1 = subject.for_metric(:metric_name, metric_type: :gauge)
metric_store1.set(labels: { foo: "1", bar: "1" }, val: 1)
Expand All @@ -184,16 +206,17 @@
metric_store1.set(labels: { bar: "1", foo: "1" }, val: 10)

expect(metric_store1.all_values).to eq(
{ foo: "1", bar: "1", pid: "12345" } => 10.0,
{ foo: "1", bar: "2", pid: "12345" } => 7.0,
{ foo: "2", bar: "1", pid: "12345" } => 3.0,
{ foo: "1", bar: "1", pid: "host1_12345" } => 10.0,
{ foo: "1", bar: "2", pid: "host1_12345" } => 7.0,
{ foo: "2", bar: "1", pid: "host1_12345" } => 3.0,
)

end
end

context "with a metric that takes MAX instead of SUM" do
it "reports the maximum values from different processes" do
allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(12345)
metric_store1 = subject.for_metric(
:metric_name,
Expand All @@ -204,6 +227,7 @@
metric_store1.set(labels: { foo: "baz" }, val: 7)
metric_store1.set(labels: { foo: "yyy" }, val: 3)

allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(23456)
metric_store2 = subject.for_metric(
:metric_name,
Expand All @@ -228,6 +252,7 @@

context "with a metric that takes MIN instead of SUM" do
it "reports the minimum values from different processes" do
allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(12345)
metric_store1 = subject.for_metric(
:metric_name,
Expand All @@ -238,6 +263,7 @@
metric_store1.set(labels: { foo: "baz" }, val: 7)
metric_store1.set(labels: { foo: "yyy" }, val: 3)

allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(23456)
metric_store2 = subject.for_metric(
:metric_name,
Expand All @@ -262,6 +288,7 @@

context "with a metric that takes ALL instead of SUM" do
it "reports all the values from different processes" do
allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(12345)
metric_store1 = subject.for_metric(
:metric_name,
Expand All @@ -272,6 +299,7 @@
metric_store1.set(labels: { foo: "baz" }, val: 7)
metric_store1.set(labels: { foo: "yyy" }, val: 3)

allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(23456)
metric_store2 = subject.for_metric(
:metric_name,
Expand All @@ -283,12 +311,12 @@
metric_store2.set(labels: { foo: "zzz" }, val: 1)

expect(metric_store1.all_values).to eq(
{ foo: "bar", pid: "12345" } => 1.0,
{ foo: "bar", pid: "23456" } => 3.0,
{ foo: "baz", pid: "12345" } => 7.0,
{ foo: "baz", pid: "23456" } => 2.0,
{ foo: "yyy", pid: "12345" } => 3.0,
{ foo: "zzz", pid: "23456" } => 1.0,
{ foo: "bar", pid: "host1_12345" } => 1.0,
{ foo: "bar", pid: "host1_23456" } => 3.0,
{ foo: "baz", pid: "host1_12345" } => 7.0,
{ foo: "baz", pid: "host1_23456" } => 2.0,
{ foo: "yyy", pid: "host1_12345" } => 3.0,
{ foo: "zzz", pid: "host1_23456" } => 1.0,
)

# Both processes should return the same value
Expand All @@ -309,14 +337,17 @@
metric_settings: { aggregation: :most_recent }
)

allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(12345)
metric_store1.set(labels: { foo: "bar" }, val: 1)

allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(23456)
metric_store2.set(labels: { foo: "bar" }, val: 3) # Supercedes 'bar' in PID 12345
metric_store2.set(labels: { foo: "baz" }, val: 2)
metric_store2.set(labels: { foo: "zzz" }, val: 1)

allow(Socket).to receive(:gethostname).and_return("host1")
allow(Process).to receive(:pid).and_return(12345)
metric_store1.set(labels: { foo: "baz" }, val: 4) # Supercedes 'baz' in PID 23456

Expand Down Expand Up @@ -347,7 +378,7 @@
truncate_calls_count = 0
allow_any_instance_of(Prometheus::Client::DataStores::DirectFileStore::FileMappedDict).
to receive(:resize_file).and_wrap_original do |original_method, *args, &block|

truncate_calls_count += 1
original_method.call(*args, &block)
end
Expand Down