HostDB: remove unused field in HostDBApplicationInfo, and update remaining types in http_data to fix broken padding. (#7264)
diff --git a/iocore/hostdb/HostDB.cc b/iocore/hostdb/HostDB.cc
index ede43d0..9ca0f4e 100644
--- a/iocore/hostdb/HostDB.cc
+++ b/iocore/hostdb/HostDB.cc
@@ -64,6 +64,10 @@
int hostdb_disable_reverse_lookup = 0;
int hostdb_max_iobuf_index = BUFFER_SIZE_INDEX_32K;
+// Verify the generic storage is sufficient to cover all alternate members.
+static_assert(sizeof(HostDBApplicationInfo::allotment) == sizeof(HostDBApplicationInfo),
+ "Generic storage for HostDBApplicationInfo is smaller than the union storage.");
+
ClassAllocator<HostDBContinuation> hostDBContAllocator("hostDBContAllocator");
// Static configuration information
diff --git a/iocore/hostdb/I_HostDBProcessor.h b/iocore/hostdb/I_HostDBProcessor.h
index d709bdf..80f9b68 100644
--- a/iocore/hostdb/I_HostDBProcessor.h
+++ b/iocore/hostdb/I_HostDBProcessor.h
@@ -83,43 +83,44 @@
// Types
//
-//
-// This structure contains the host information required by
-// the application. Except for the initial fields it
-// is treated as opaque by the database.
-//
-
+/** Host information metadata used by various parts of HostDB.
+ * It is stored as generic data in the cache.
+ *
+ * As a @c union only one of the members is valid, Which one depends on context data in the
+ * @c HostDBInfo. This data is written literally to disk therefore if any change is made,
+ * the @c object_version for the cache must be updated by modifying @c HostDBInfo::version.
+ *
+ * @see HostDBInfo::version
+ */
union HostDBApplicationInfo {
+ /// Generic storage. This is verified to be the size of the union.
struct application_data_allotment {
unsigned int application1;
unsigned int application2;
} allotment;
+ enum HttpVersion : uint8_t {
+ HTTP_VERSION_UNDEFINED = 0,
+ HTTP_VERSION_09 = 1,
+ HTTP_VERSION_10 = 2,
+ HTTP_VERSION_11 = 3,
+ };
+
//////////////////////////////////////////////////////////
// http server attributes in the host database //
// //
- // http_version - one of HttpVersion_t //
- // keep_alive_timeout - in seconds. (up to 63 seconds). //
+ // http_version - one of HttpVersion //
// last_failure - UNIX time for the last time //
// we tried the server & failed //
// fail_count - Number of times we tried and //
// and failed to contact the host //
//////////////////////////////////////////////////////////
struct http_server_attr {
- unsigned int http_version : 3;
- unsigned int keepalive_timeout : 6;
- unsigned int fail_count : 8;
- unsigned int unused1 : 8;
- unsigned int last_failure : 32;
+ uint32_t last_failure;
+ HttpVersion http_version;
+ uint8_t fail_count;
} http_data;
- enum HttpVersion_t {
- HTTP_VERSION_UNDEFINED = 0,
- HTTP_VERSION_09 = 1,
- HTTP_VERSION_10 = 2,
- HTTP_VERSION_11 = 3,
- };
-
struct application_data_rr {
unsigned int offset;
} rr;
@@ -161,11 +162,15 @@
ioBufAllocator[_iobuffer_index].free_void((void *)(this));
}
- // return a version number-- so we can manage compatibility with the marshal/unmarshal
+ /// Effectively the @c object_version for cache data.
+ /// This is used to indicate incompatible changes in the binary layout of HostDB records.
+ /// It must be updated if any such change is made, even if it is functionally equivalent.
static ts::VersionNumber
version()
{
- return ts::VersionNumber(1, 0);
+ /// - 1.0 Initial version.
+ /// - 1.1 tweak HostDBApplicationInfo::http_data.
+ return ts::VersionNumber(1, 1);
}
static HostDBInfo *
diff --git a/proxy/http/HttpTransact.h b/proxy/http/HttpTransact.h
index 8b062df..bfca7f5 100644
--- a/proxy/http/HttpTransact.h
+++ b/proxy/http/HttpTransact.h
@@ -682,10 +682,10 @@
DNSLookupInfo dns_info;
RedirectInfo redirect_info;
OutboundConnTrack::TxnState outbound_conn_track_state;
- unsigned int updated_server_version = HostDBApplicationInfo::HTTP_VERSION_UNDEFINED;
- bool force_dns = false;
- MgmtByte cache_open_write_fail_action = 0;
- bool is_revalidation_necessary = false; // Added to check if revalidation is necessary - YTS Team, yamsat
+ HostDBApplicationInfo::HttpVersion updated_server_version = HostDBApplicationInfo::HTTP_VERSION_UNDEFINED;
+ bool force_dns = false;
+ MgmtByte cache_open_write_fail_action = 0;
+ bool is_revalidation_necessary = false; // Added to check if revalidation is necessary - YTS Team, yamsat
ConnectionAttributes client_info;
ConnectionAttributes parent_info;
ConnectionAttributes server_info;
