fix: handling default handling where subsetSize = 0 means the entire pool

Change-Id: Ifb6c293e355d337d457d3b76efe4e21924f80f81

Author: igorbernstein2

google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/data/v2/internal/session/LeastInFlightPicker.java

@@ -46,7 +46,10 @@ Optional<SessionHandle> pickSession() {
     List<AfeHandle> candidates = new ArrayList<>(readyAfes);
     int bestCost = Integer.MAX_VALUE;
     AfeHandle bestAfe = null;
-    long iterations = Math.min(options.getRandomSubsetSize(), readyAfes.size());
+    long iterations = readyAfes.size();
+    if (options.getRandomSubsetSize() > 0) {
+      iterations = Math.min(options.getRandomSubsetSize(), iterations);
+    }
 
     // Partial Fisher-Yates shuffle.
     for (int i = 0; i < iterations; i++) {

google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/data/v2/internal/session/LeastLatencyPicker.java

@@ -46,7 +46,11 @@ Optional<SessionHandle> pickSession() {
     List<AfeHandle> candidates = new ArrayList<>(readyAfes);
     double bestCost = Double.MAX_VALUE;
     AfeHandle bestAfe = null;
-    long iterations = Math.min(options.getRandomSubsetSize(), readyAfes.size());
+    long iterations = readyAfes.size();
+
+    if (options.getRandomSubsetSize() > 0) {
+      iterations = Math.min(options.getRandomSubsetSize(), iterations);
+    }
 
     // Partial Fisher-Yates shuffle.
     for (int i = 0; i < iterations; i++) {