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require 'spec_helper'
require 'prometheus/client/helper/mmaped_file'
require 'prometheus/client/page_size'
describe Prometheus::Client::Helper::MmapedFile do
let(:filename) { Dir::Tmpname.create('mmaped_file_') {} }
after do
File.delete(filename) if File.exist?(filename)
end
describe '.open' do
it 'initialize PRIVATE mmaped file read only' do
expect(described_class).to receive(:new).with(filename).and_call_original
expect(described_class.open(filename)).to be_instance_of(described_class)
end
end
context 'file does not exist' do
let (:subject) { described_class.open(filename) }
it 'creates and initializes file correctly' do
expect(File.exist?(filename)).to be_falsey
subject
expect(File.exist?(filename)).to be_truthy
end
it 'creates a file with minimum initial size' do
expect(File.size(subject.filepath)).to eq(subject.send(:initial_mmap_file_size))
end
context 'when initial mmap size is larger' do
let(:page_size) { Prometheus::Client::PageSize.page_size }
let (:initial_mmap_file_size) { page_size + 1024 }
before do
allow_any_instance_of(described_class).to receive(:initial_mmap_file_size).and_return(initial_mmap_file_size)
end
it 'creates a file with increased minimum initial size' do
expect(File.size(subject.filepath)).to eq(page_size * 2);
end
end
end
describe '.ensure_exclusive_file' do
let(:tmpdir) { Dir.mktmpdir('mmaped_file') }
let(:pid) { 'pid' }
before do
allow(Prometheus::Client.configuration).to receive(:multiprocess_files_dir).and_return(tmpdir)
allow(Prometheus::Client.configuration).to receive(:pid_provider).and_return(pid.method(:to_s))
end
context 'when no files are already locked' do
it 'provides first possible filename' do
expect(described_class.ensure_exclusive_file('mmaped_file'))
.to match(/.*mmaped_file_pid-0\.db/)
end
it 'provides first and second possible filenames for two invocations' do
expect(described_class.ensure_exclusive_file('mmaped_file'))
.to match(/.*mmaped_file_pid-0\.db/)
expect(described_class.ensure_exclusive_file('mmaped_file'))
.to match(/.*mmaped_file_pid-1\.db/)
end
end
context 'when first possible file exists for current file ID' do
let(:first_mmaped_file) { described_class.ensure_exclusive_file('mmaped_file') }
before do
first_mmaped_file
end
context 'first file is unlocked' do
before do
Prometheus::Client::Helper::FileLocker.unlock(first_mmaped_file)
end
it 'provides first possible filename discarding the lock' do
expect(described_class.ensure_exclusive_file('mmaped_file'))
.to match(/.*mmaped_file_pid-0\.db/)
end
it 'provides second possible filename for second invocation' do
expect(described_class.ensure_exclusive_file('mmaped_file'))
.to match(/.*mmaped_file_pid-0\.db/)
expect(described_class.ensure_exclusive_file('mmaped_file'))
.to match(/.*mmaped_file_pid-1\.db/)
end
end
context 'first file is not unlocked' do
it 'provides second possible filename' do
expect(described_class.ensure_exclusive_file('mmaped_file'))
.to match(/.*mmaped_file_pid-1\.db/)
end
it 'provides second and third possible filename for two invocations' do
expect(described_class.ensure_exclusive_file('mmaped_file'))
.to match(/.*mmaped_file_pid-1\.db/)
expect(described_class.ensure_exclusive_file('mmaped_file'))
.to match(/.*mmaped_file_pid-2\.db/)
end
end
end
end
end
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