Merge branch 'jt/odb-transaction-write' into next

ODB transaction interface is being reworked to explicitly handle
object writes.

* jt/odb-transaction-write:
  odb/transaction: make `write_object_stream()` pluggable
  object-file: generalize packfile writes to use odb_write_stream
  object-file: avoid fd seekback by checking object size upfront
  object-file: remove flags from transaction packfile writes
  odb: update `struct odb_write_stream` read() callback
  odb/transaction: use pluggable `begin_transaction()`
  odb: split `struct odb_transaction` into separate header

diff --cc Makefile
Simple merge

diff --cc builtin/unpack-objects.c
Simple merge

diff --cc cache-tree.c
Simple merge

diff --cc meson.build
Simple merge

diff --cc object-file.c
Simple merge

diff --cc odb.c
Simple merge

diff --cc odb.h
index 3a711f6547bb002739638149e13c49a0a98aed40,6faeaa05891d7bb5682b53c0a687ce940bcde743..9eb8355aca540be9aa9472f0fa2166eaf3aa04e7
--- 1/odb.h
--- 2/odb.h
+++ b/odb.h
@@@ -29,24 -31,10 +29,6 @@@ extern int fetch_if_missing
   */
  char *compute_alternate_path(const char *path, struct strbuf *err);
  
- /*
-  * A transaction may be started for an object database prior to writing new
-  * objects via odb_transaction_begin(). These objects are not committed until
-  * odb_transaction_commit() is invoked. Only a single transaction may be pending
-  * at a time.
-  *
-  * Each ODB source is expected to implement its own transaction handling.
-  */
- struct odb_transaction;
- typedef void (*odb_transaction_commit_fn)(struct odb_transaction *transaction);
- struct odb_transaction {
-       /* The ODB source the transaction is opened against. */
-       struct odb_source *source;
- 
-       /* The ODB source specific callback invoked to commit a transaction. */
-       odb_transaction_commit_fn commit;
- };
 -struct packed_git;
 -struct packfile_store;
 -struct cached_object_entry;
--
  /*
   * The object database encapsulates access to objects in a repository. It
   * manages one or more sources that store the actual objects which are

diff --cc odb/streaming.c
Simple merge

diff --cc odb/streaming.h
Simple merge

diff --cc read-cache.c
Simple merge