Apply timeout to persistent connections

[camfilho]

The persistent socket is built with HTTP.persistent(...) alone, so the timeout option only reaches the non-persistent path in execute_request. Since persistent: true is the default, most clients make requests with no client-side timeout:

client = SerpApi::Client.new(api_key: 'x', timeout: 5)
client.socket.default_options.timeout_options # => {}

A request on a half-open connection then waits on the OS TCP retry limit, and a server that accepts but never responds can block the caller indefinitely.

Change: build the socket with HTTP.timeout(timeout).persistent(...). http.rb resets the global timeout counter after each response on a kept-alive connection, so long-lived clients are not cut off after timeout seconds in total.

The README options table describes timeout as applying to non-persistent requests only, while its examples pass timeout: with persistent: true. I've updated the table to match; if the current behavior is intended, happy to close this.

Tested:

• New spec applies the timeout to the persistent socket fails before the change (got: {}) and passes after. It makes no network call.
• rubocop lib spec: no offenses.
• Two live searches on one persistent client with timeout: 30: both succeeded over the same socket, and close returned :clean.

This fix was also part of #22, which was closed by its author along with several unrelated changes. This PR only carries the timeout fix.

[strzibny]

@camfilho Looks good to me, thanks for sending the fix!

One small thing for tests to run green for me:

diff --git a/spec/serpapi/client/image_api_spec.rb b/spec/serpapi/client/image_api_spec.rb
index 0fc4f5d..3503479 100644
--- a/spec/serpapi/client/image_api_spec.rb
+++ b/spec/serpapi/client/image_api_spec.rb
@@ -13,7 +13,7 @@ describe 'Image API' do
   let(:client) { SerpApi::Client.new(api_key: api_key) }

   before do
-    allow(HTTP).to receive(:persistent).and_return(socket)
+    allow(HTTP).to receive(:timeout).and_return(double(persistent: socket))
     allow(response).to receive(:flush)
   end

Please update.

[camfilho]

@strzibny Thanks for the review! Applied your suggested change to image_api_spec.rb in 1c6edbf. The image API specs pass again along with the new timeout spec, and rubocop is clean.

[strzibny]

@camfilho can you please rebase, we don't have README.md.erb any longer.

[camfilho]

Done strzibny

[strzibny]

Thank you @camfilho!