Add async_files library to support filesystem buffering and filesystem caching (#20332)

Signed-off-by: Raven Black <ravenblack@dropbox.com>

Mirrored from https://github.com/envoyproxy/envoy @ 18c779af9106a1d85203621c9f4453d5901744e8

BUILD

@@ -126,6 +126,7 @@ proto_library(
         "//envoy/extensions/clusters/aggregate/v3:pkg",
         "//envoy/extensions/clusters/dynamic_forward_proxy/v3:pkg",
         "//envoy/extensions/clusters/redis/v3:pkg",
+        "//envoy/extensions/common/async_files/v3:pkg",
         "//envoy/extensions/common/dynamic_forward_proxy/v3:pkg",
         "//envoy/extensions/common/matching/v3:pkg",
         "//envoy/extensions/common/ratelimit/v3:pkg",

envoy/extensions/common/async_files/v3/BUILD

@@ -0,0 +1,12 @@
+# DO NOT EDIT. This file is generated by tools/proto_format/proto_sync.py.
+
+load("@envoy_api//bazel:api_build_system.bzl", "api_proto_package")
+
+licenses(["notice"])  # Apache 2
+
+api_proto_package(
+    deps = [
+        "@com_github_cncf_udpa//udpa/annotations:pkg",
+        "@com_github_cncf_udpa//xds/annotations/v3:pkg",
+    ],
+)

envoy/extensions/common/async_files/v3/async_file_manager.proto

@@ -0,0 +1,41 @@
+syntax = "proto3";
+
+package envoy.extensions.common.async_files.v3;
+
+import "xds/annotations/v3/status.proto";
+
+import "udpa/annotations/status.proto";
+import "validate/validate.proto";
+
+option java_package = "io.envoyproxy.envoy.extensions.common.async_files.v3";
+option java_outer_classname = "AsyncFileManagerProto";
+option java_multiple_files = true;
+option go_package = "github.com/envoyproxy/go-control-plane/envoy/extensions/common/async_files/v3;async_filesv3";
+option (udpa.annotations.file_status).package_version_status = ACTIVE;
+option (xds.annotations.v3.file_status).work_in_progress = true;
+
+// [#protodoc-title: AsyncFileManager configuration]
+
+// Configuration to instantiate or select a singleton `AsyncFileManager`.
+message AsyncFileManagerConfig {
+  message ThreadPool {
+    // The number of threads to use. If unset or zero, will default to the number
+    // of concurrent threads the hardware supports. This default is subject to
+    // change if performance analysis suggests it.
+    uint32 thread_count = 1;
+  }
+
+  // An optional identifier for the manager. An empty string is a valid identifier
+  // for a common, default `AsyncFileManager`.
+  //
+  // Reusing the same id with different configurations in the same envoy instance
+  // is an error.
+  string id = 1;
+
+  oneof manager_type {
+    option (validate.required) = true;
+
+    // Configuration for a thread-pool based async file manager.
+    ThreadPool thread_pool = 2;
+  }
+}

versioning/BUILD

@@ -63,6 +63,7 @@ proto_library(
         "//envoy/extensions/clusters/aggregate/v3:pkg",
         "//envoy/extensions/clusters/dynamic_forward_proxy/v3:pkg",
         "//envoy/extensions/clusters/redis/v3:pkg",
+        "//envoy/extensions/common/async_files/v3:pkg",
         "//envoy/extensions/common/dynamic_forward_proxy/v3:pkg",
         "//envoy/extensions/common/matching/v3:pkg",
         "//envoy/extensions/common/ratelimit/v3:pkg",