Add GCS_READ_CACHE_DISABLED explicit env var to GcsFileSystem

PiperOrigin-RevId: 198658074

diff --git a/tensorflow/core/platform/cloud/gcs_file_system.cc b/tensorflow/core/platform/cloud/gcs_file_system.cc
index d3a1489..22ae612 100644 (file)
--- a/tensorflow/core/platform/cloud/gcs_file_system.cc
+++ b/tensorflow/core/platform/cloud/gcs_file_system.cc
@@ -64,6 +64,10 @@ constexpr uint64 HTTP_CODE_RESUME_INCOMPLETE = 308;
 // The environment variable that overrides the size of the readahead buffer.
 // DEPRECATED. Use GCS_BLOCK_SIZE_MB instead.
 constexpr char kReadaheadBufferSize[] = "GCS_READAHEAD_BUFFER_SIZE_BYTES";
+// The environment variable that disables the GCS block cache for reads.
+// This is the explicit alternative to setting BLOCK_SIZE or MAX_SIZE to 0, and
+// takes precedence over either of those environment variables.
+constexpr char kReadCacheDisabled[] = "GCS_READ_CACHE_DISABLED";
 // The environment variable that overrides the block size for aligned reads from
 // GCS. Specified in MB (e.g. "16" = 16 x 1024 x 1024 = 16777216 bytes).
 constexpr char kBlockSize[] = "GCS_READ_CACHE_BLOCK_SIZE_MB";
@@ -623,6 +627,10 @@ GcsFileSystem::GcsFileSystem()
   if (GetEnvVar(kMaxStaleness, strings::safe_strtou64, &value)) {
     max_staleness = value;
   }
+  if (std::getenv(kReadCacheDisabled)) {
+    // Setting either to 0 disables the cache; set both for good measure.
+    block_size = max_bytes = 0;
+  }
   file_block_cache_ = MakeFileBlockCache(block_size, max_bytes, max_staleness);
   // Apply overrides for the stat cache max age and max entries, if provided.
   uint64 stat_cache_max_age = kStatCacheDefaultMaxAge;

diff --git a/tensorflow/core/platform/cloud/ram_file_block_cache.h b/tensorflow/core/platform/cloud/ram_file_block_cache.h
index 2303f9c..46fb9a3 100644 (file)
--- a/tensorflow/core/platform/cloud/ram_file_block_cache.h
+++ b/tensorflow/core/platform/cloud/ram_file_block_cache.h
@@ -60,6 +60,8 @@ class RamFileBlockCache : public FileBlockCache {
       pruning_thread_.reset(env_->StartThread(ThreadOptions(), "TF_prune_FBC",
                                               [this] { Prune(); }));
     }
+    VLOG(1) << "GCS file block cache is "
+            << (IsCacheEnabled() ? "enabled" : "disabled");
   }
 
   ~RamFileBlockCache() override {