(MAINT) Reduce redis Calls in API

The return values from most redis calls inform the caller of whether a
key or hash value exists. Several exists() calls can be removed in
favor of this approach.

Updated spec tests to account for a removal of exists() and ismember()
calls in API tests.

lib/vmpooler/api/v1.rb

@@ -385,12 +385,11 @@ module Vmpooler
 
       params[:hostname] = hostname_shorten(params[:hostname], config['domain'])
 
-      if backend.exists('vmpooler__vm__' + params[:hostname])
+      rdata = backend.hgetall('vmpooler__vm__' + params[:hostname])
+      unless rdata.empty?
         status 200
         result['ok'] = true
 
-        rdata = backend.hgetall('vmpooler__vm__' + params[:hostname])
-
         result[params[:hostname]] = {}
 
         result[params[:hostname]]['template'] = rdata['template']
@@ -438,13 +437,11 @@ module Vmpooler
 
       params[:hostname] = hostname_shorten(params[:hostname], config['domain'])
 
-      if backend.exists('vmpooler__vm__' + params[:hostname])
       rdata = backend.hgetall('vmpooler__vm__' + params[:hostname])
-
+      unless rdata.empty?
         need_token! if rdata['token:token']
 
-        if backend.sismember('vmpooler__running__' + rdata['template'], params[:hostname])
+        if backend.srem('vmpooler__running__' + rdata['template'], params[:hostname])
-          backend.srem('vmpooler__running__' + rdata['template'], params[:hostname])
           backend.sadd('vmpooler__completed__' + rdata['template'], params[:hostname])
 
           status 200
@@ -554,7 +551,7 @@ module Vmpooler
 
       params[:hostname] = hostname_shorten(params[:hostname], config['domain'])
 
-      if backend.exists('vmpooler__vm__' + params[:hostname]) and backend.hget('vmpooler__vm__' + params[:hostname], 'snapshot:' + params[:snapshot])
+      unless backend.hget('vmpooler__vm__' + params[:hostname], 'snapshot:' + params[:snapshot]).to_i.zero?
         backend.sadd('vmpooler__tasks__snapshot-revert', params[:hostname] + ':' + params[:snapshot])
 
         status 202

spec/vmpooler/api/v1_spec.rb

@@ -438,9 +438,7 @@ describe Vmpooler::API::V1 do
         let(:config) { { auth: false } }
 
         it 'does not delete a non-existant VM' do
-          expect(redis).to receive(:exists).with('vmpooler__vm__testhost').and_return false
+          expect(redis).to receive(:hgetall).and_return({})
-          expect(redis).not_to receive(:sismember)
-          expect(redis).not_to receive(:hgetall)
           expect(redis).not_to receive(:sadd)
           expect(redis).not_to receive(:srem)
 
@@ -453,11 +451,9 @@ describe Vmpooler::API::V1 do
         end
 
         it 'deletes an existing VM' do
-          expect(redis).to receive(:exists).with('vmpooler__vm__testhost').and_return '1'
-          expect(redis).to receive(:sismember).with('vmpooler__running__pool1', 'testhost').and_return '1'
           expect(redis).to receive(:hgetall).with('vmpooler__vm__testhost').and_return({"template" => "pool1"})
+          expect(redis).to receive(:srem).and_return(true)
           expect(redis).to receive(:sadd)
-          expect(redis).to receive(:srem)
 
           delete "#{prefix}/vm/testhost"
 
@@ -473,11 +469,9 @@ describe Vmpooler::API::V1 do
 
         context '(checked-out without token)' do
           it 'deletes a VM without supplying a token' do
-            expect(redis).to receive(:exists).with('vmpooler__vm__testhost').and_return '1'
-            expect(redis).to receive(:sismember).with('vmpooler__running__pool1', 'testhost').and_return '1'
             expect(redis).to receive(:hgetall).with('vmpooler__vm__testhost').and_return({"template" => "pool1"})
+            expect(redis).to receive(:srem).and_return(true)
             expect(redis).to receive(:sadd)
-            expect(redis).to receive(:srem)
 
             delete "#{prefix}/vm/testhost"
 
@@ -490,7 +484,6 @@ describe Vmpooler::API::V1 do
 
         context '(checked-out with token)' do
           it 'fails to delete a VM without supplying a token' do
-            expect(redis).to receive(:exists).with('vmpooler__vm__testhost').and_return '1'
             expect(redis).to receive(:hgetall).with('vmpooler__vm__testhost').and_return({"template" => "pool1", "token:token" => "abcdefghijklmnopqrstuvwxyz012345"})
             expect(redis).not_to receive(:sadd)
             expect(redis).not_to receive(:srem)
@@ -504,11 +497,9 @@ describe Vmpooler::API::V1 do
           end
 
           it 'deletes a VM when token is supplied' do
-            expect(redis).to receive(:exists).with('vmpooler__vm__testhost').and_return '1'
             expect(redis).to receive(:hgetall).with('vmpooler__vm__testhost').and_return({"template" => "pool1", "token:token" => "abcdefghijklmnopqrstuvwxyz012345"})
-            expect(redis).to receive(:sismember).with('vmpooler__running__pool1', 'testhost').and_return '1'
+            expect(redis).to receive(:srem).and_return(true)
             expect(redis).to receive(:sadd)
-            expect(redis).to receive(:srem)
 
             delete "#{prefix}/vm/testhost", "", {
               'HTTP_X_AUTH_TOKEN' => 'abcdefghijklmnopqrstuvwxyz012345'
@@ -571,7 +562,6 @@ describe Vmpooler::API::V1 do
         let(:config) { { auth: false } }
 
         it 'reverts to a snapshot' do
-          expect(redis).to receive(:exists).with('vmpooler__vm__testhost').and_return(1)
           expect(redis).to receive(:hget).with('vmpooler__vm__testhost', 'snapshot:testsnapshot').and_return(1)
           expect(redis).to receive(:sadd)
 
@@ -596,7 +586,6 @@ describe Vmpooler::API::V1 do
         end
 
         it 'reverts to a snapshot if authed' do
-          expect(redis).to receive(:exists).with('vmpooler__vm__testhost').and_return(1)
           expect(redis).to receive(:hget).with('vmpooler__vm__testhost', 'snapshot:testsnapshot').and_return(1)
           expect(redis).to receive(:sadd)