sstables: allow non-traditional characters in table name

The goal of this patch is to fix issue #5280, a rather serious Alternator
bug, where Scylla fails to restart when an Alternator table has secondary
indexes (LSI or GSI).

Traditionally, Cassandra allows table names to contain only alphanumeric
characters and underscores. However, most of our internal implementation
doesn't actually have this restriction. So Alternator uses the characters
':' and '!' in the table names to mark global and local secondary indexes,
respectively. And this actually works. Or almost...

This patch fixes a problem of listing, during boot, the sstables stored
for tables with such non-traditional names. The sstable listing code
needlessly assumes that the *directory* name, i.e., the CF names, matches
the "\w+" regular expression. When an sstable is found in a directory not
matching such regular expression, the boot fails. But there is no real
reason to require such a strict regular expression. So this patch relaxes
this requirement, and allows Scylla to boot with Alternator's GSI and LSI
tables and their names which include the ":" and "!" characters, and in
fact any other name allowed as a directory name.

Fixes #5280.

Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20191114153811.17386-1-nyh@scylladb.com>
(cherry picked from commit 2fb2eb27a2)

SCYLLA-VERSION-GEN

@@ -1,7 +1,7 @@
 #!/bin/sh
 
 PRODUCT=scylla
-VERSION=666.development
+VERSION=3.2.rc0
 
 if test -f version
 then

sstables/sstables.cc

@@ -2699,7 +2699,7 @@ entry_descriptor entry_descriptor::make_descriptor(sstring sstdir, sstring fname
     static std::regex la_mc("(la|mc)-(\\d+)-(\\w+)-(.*)");
     static std::regex ka("(\\w+)-(\\w+)-ka-(\\d+)-(.*)");
 
-    static std::regex dir(".*/([^/]*)/(\\w+)-[\\da-fA-F]+(?:/staging|/upload|/snapshots/[^/]+)?/?");
+    static std::regex dir(".*/([^/]*)/([^/]+)-[\\da-fA-F]+(?:/staging|/upload|/snapshots/[^/]+)?/?");
 
     std::smatch match;
 

table.cc

@@ -292,7 +292,7 @@ create_single_key_sstable_reader(column_family* cf,
         filter_sstable_for_reader(sstables->select(pr), *cf, schema, pr, key, slice)
         | boost::adaptors::transformed([&] (const sstables::shared_sstable& sstable) {
             tracing::trace(trace_state, "Reading key {} from sstable {}", pr, seastar::value_of([&sstable] { return sstable->get_filename(); }));
-            return sstable->read_row_flat(schema, pr.start()->value(), slice, pc, resource_tracker, std::move(trace_state), fwd);
+            return sstable->read_row_flat(schema, pr.start()->value(), slice, pc, resource_tracker, trace_state, fwd);
         })
     );
     if (readers.empty()) {
@@ -315,7 +315,7 @@ flat_mutation_reader make_range_sstable_reader(schema_ptr s,
 {
     auto reader_factory_fn = [s, &slice, &pc, resource_tracker, trace_state, fwd, fwd_mr, &monitor_generator]
             (sstables::shared_sstable& sst, const dht::partition_range& pr) mutable {
-        return sst->read_range_rows_flat(s, pr, slice, pc, resource_tracker, std::move(trace_state), fwd, fwd_mr, monitor_generator(sst));
+        return sst->read_range_rows_flat(s, pr, slice, pc, resource_tracker, trace_state, fwd, fwd_mr, monitor_generator(sst));
     };
     return make_combined_reader(s, std::make_unique<incremental_reader_selector>(s,
                     std::move(sstables),
@@ -587,7 +587,7 @@ flat_mutation_reader make_local_shard_sstable_reader(schema_ptr s,
     auto reader_factory_fn = [s, &slice, &pc, resource_tracker, trace_state, fwd, fwd_mr, &monitor_generator]
             (sstables::shared_sstable& sst, const dht::partition_range& pr) mutable {
         flat_mutation_reader reader = sst->read_range_rows_flat(s, pr, slice, pc,
-                resource_tracker, std::move(trace_state), fwd, fwd_mr, monitor_generator(sst));
+                resource_tracker, trace_state, fwd, fwd_mr, monitor_generator(sst));
         if (sst->is_shared()) {
             using sig = bool (&)(const dht::decorated_key&);
             reader = make_filtering_reader(std::move(reader), sig(belongs_to_current_shard));