[fix](cloud) fix BlockFileCache::get_or_set crash (#44013)

This is a Plan-B fix, the root cause is under study:

2# JVM_handle_linux_signal in
/usr/lib/jvm/java-17-openjdk-amd64/lib/server/libjvm.so
 3# 0x00007F8CFE720520 in /lib/x86_64-linux-gnu/libc.so.6
4# std::_Rb_tree_decrement(std::_Rb_tree_node_base*) at
../../../../../libstdc++-v3/src/c++98/tree.cc:123
5#
doris::io::BlockFileCache::get_impl[abi:cxx11](doris::io::UInt128Wrapper
const&, doris::io::CacheContext const&, doris::io::FileBlock::Range
const&, std::lock_guard<std::mutex>&) at
/home/zcp/repo_center/doris_branch-3.0/doris/be/src/io/cache/block_file_cache.cpp:365
6# doris::io::BlockFileCache::get_or_set(doris::io::UInt128Wrapper
const&, unsigned long, unsigned long, doris::io::CacheContext&) at
/home/zcp/repo_center/doris_branch-3.0/doris/be/src/io/cache/block_file_cache.cpp:662
7# doris::io::CachedRemoteFileReader::read_at_impl(unsigned long,
doris::Slice, unsigned long*, doris::io::IOContext const*) at
/home/zcp/repo_center/doris_branch-3.0/doris/be/src/io/cache/cached_remote_file_reader.cpp:179


Signed-off-by: zhengyu <[email protected]>

be/src/io/cache/block_file_cache.cpp

@@ -393,6 +393,15 @@ FileBlocks BlockFileCache::get_impl(const UInt128Wrapper& hash, const CacheConte
 
     auto& file_blocks = it->second;
     DCHECK(!file_blocks.empty());
+    if (file_blocks.empty()) {
+        LOG(WARNING) << "file_blocks is empty for hash=" << hash.to_string()
+                     << " cache type=" << context.cache_type
+                     << " cache expiration time=" << context.expiration_time
+                     << " cache range=" << range.left << " " << range.right
+                     << " query id=" << context.query_id;
+        _files.erase(hash);
+        return {};
+    }
     // change to ttl if the blocks aren't ttl
     if (context.cache_type == FileCacheType::TTL && _key_to_time.find(hash) == _key_to_time.end()) {
         for (auto& [_, cell] : file_blocks) {