sstableloader: Handle dead liveness info (ttl == expired)

Refs scylla-enterprise#920

Liveness can (apparently) be already marked dead -> invalid ttl
value. We cannot (I think) just skip the row since according to
docs it serves a purpose still. We can however mark it as
immedetiatly expiring (next second) and assume this will make
the end result be the same even when imported (and compacted).
Message-Id: <20190618152218.11389-1-calle@scylladb.com>

Author: Calle Wilund

src/java/com/scylladb/tools/SSTableToCQL.java

@@ -607,6 +607,13 @@ private void writeUsingTTL(StringBuilder buf, Map<String, Object> params) {
                 ensureWhitespace(buf);
 
                 int adjustedTTL = ttl;
+
+                // if the row is in fact not actually live, i.e. already explicitly 
+                // marked dead by ttl == expired, set it to a minimal value 
+                // so we can hope it expires again as soon as possible. 
+                if (adjustedTTL == LivenessInfo.EXPIRED_LIVENESS_TTL) {
+                    adjustedTTL = 1;
+                }
 
                 if (timestamp == invalidTimestamp) {
                     buf.append("USING ");
@@ -619,7 +626,7 @@ private void writeUsingTTL(StringBuilder buf, Map<String, Object> params) {
                     if (exp < now) {
                         adjustedTTL = 1; // 0 -> no ttl. 1 should disappear fast enoug
                     } else {
-                        adjustedTTL = (int)Math.min(ttl, exp - now);
+                        adjustedTTL = (int)Math.min(adjustedTTL, exp - now);
                     }                    
                 }
                 buf.append(" TTL :" + TTL_VAR_NAME);