From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f48.google.com (mail-wm1-f48.google.com [209.85.128.48]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 57033202C5C for ; Mon, 19 May 2025 09:58:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.48 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747648701; cv=none; b=o3kNwosz1qZKjs8tEMZmB3Q+Hx0acaigluDIi61cv9+2ZKKeWeNDkp/F1w/cgp9Y19jWUetdZefcdNDNTf4/1HQtiiN830WMx6VC9olEdfJX1xXSohVeB0UoBpWQvNEdMIqN708cyuidw9MM6ye6Odi/XlnuA5T0iiFul5wezx4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747648701; c=relaxed/simple; bh=abyBqfybBCnH7UU8keEbMrkjS2R1G1iKu6KpY6Wf2qg=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=O6EmcVkJpeSVAFw3g6f4RdL358U+iO8Md+BHToLq9dzwcsfzM42glBv1ImWgzu6NtBQwkfG4cnXUUGU54PuaRSDOJrJfUlcoDeOGAUnJStD7RNBWuE8NKm7QBDNiGRMrLGs7On60Z8ZsJWlqb8Aa5yDEH79VXUNUMgOSzsrDhfU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=GL3gIiBd; arc=none smtp.client-ip=209.85.128.48 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="GL3gIiBd" Received: by mail-wm1-f48.google.com with SMTP id 5b1f17b1804b1-43cfe63c592so45199015e9.2 for ; Mon, 19 May 2025 02:58:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1747648697; x=1748253497; darn=vger.kernel.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=lj9eQDX3sobCZCyoVfkvwTuMrelUWg1pTogGh57NZWI=; b=GL3gIiBdGOANR4hTZYsdzkraAJqIADCiEF+KgjPpTQ1vFLSypKAfU7dpXfRNN+S3Hh PeArgn3AkloCOAXSTYJ2FLf4iqNP4Saaaq+C73P2eq9GJHqVLyjp20yAtQAzfyRFe1fO nZ89Nqe4Wfmzh0qBEuV9cXt2vekayU/IefKdes1IPfVq8w9PzpLcEMfGG7N458nuCnyT +2pmbG2A+VWKywJsFEqA5xmuSRYGoWib4+hp7wFvIpo21+ie4dELuNEnO9TDbu3GVW5Z 4XdVShTFwRoscV2wBLdV2Zayi9xhuQl5zCNw6I9qNZRninbC12rcguXqXYxnNkMTFEPu panA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1747648697; x=1748253497; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=lj9eQDX3sobCZCyoVfkvwTuMrelUWg1pTogGh57NZWI=; b=rwQhxXrhxtcHt7dQr4aEI0xfErbh1m9DbLX/D25st32q3DoW6hVcZH+FOIXzmzc1Mi ZkFcDPOQ0iB2LxYFU5iQa7oUv1Ap8DW7ljVmVwtzeLgyy9lAghJVW5C5gOJq0P00TP9i 9Nf2GH75SFKGrIjKeoHZ+AvI7H3iFAYwyflI1oYhjH3ShZ/nwWL98Q+iTw1nxKTmO7fi juNzw7FfZeGo+sc3Bfp37yjlIGP/WHvNwq1ofDsR0O70FDvbp2x7NdTElKOaDkBPV/VA hnGHOGEFOaLr1tXvC9Pajoujsln1fVd8Fe5xv6PSaIQdCO5NvPeygXJvYjH0y3KKttLw pKmw== X-Gm-Message-State: AOJu0YwTZ67D5JfECmhsYVVgesTUlwi1OabrzVN8hPIsvJJ/+opGmypP nBMFH4tgs+fbAOeNhdUY/UfqkBnl9IJKFU9mLiAUgpka1STyD2DlJdpz X-Gm-Gg: ASbGncvnwVAFCKTfpt7c/NSJuPph16AURhYrHTaezE22LhvRxUVKuS9ilMnPyigYynM pZww5ZvnRecfpOKYrvyT7qpE4Y2X6TN5d/TbehkJQRaSsKL4m+a5CSk/SEV5cxvEp3FOGOOcv6W yreOzRxNit9glEJIEYZi3iyZ3NzfkkKsQ2MJZy8GGyut7j+q+XXicEPP53cqMsBu2M5tMhPcivG mm8S2FUX+vlKe1iU0nqCqWXhT7ReGAafKoTDuWVQFngglRxU68zL2fey0BEZSZDbnUkarPCCbON qA5y8ojizbCbiaQCg0/TIAXKtd302Dpo64c= X-Google-Smtp-Source: AGHT+IHuIyL9ztMuowx/zFHG+ZyJOY1o7cgdHO1kVT86WMOggPgWshcs4MHWP1Wrec29Wrg3k1ddXQ== X-Received: by 2002:a05:6000:2af:b0:38d:d371:e04d with SMTP id ffacd0b85a97d-3a35c835b52mr9875565f8f.34.1747648697357; Mon, 19 May 2025 02:58:17 -0700 (PDT) Received: from [127.0.0.2] ([2a02:2455:8268:bc00:b2fc:6161:a86b:8382]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-442fa3e2ce5sm152811285e9.13.2025.05.19.02.58.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 May 2025 02:58:17 -0700 (PDT) From: Karthik Nayak Date: Mon, 19 May 2025 11:58:07 +0200 Subject: [PATCH v3 2/4] fetch: use batched reference updates Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Message-Id: <20250519-501-update-git-fetch-1-to-use-partial-transactions-v3-2-6cdfd4f769b9@gmail.com> References: <20250519-501-update-git-fetch-1-to-use-partial-transactions-v3-0-6cdfd4f769b9@gmail.com> In-Reply-To: <20250519-501-update-git-fetch-1-to-use-partial-transactions-v3-0-6cdfd4f769b9@gmail.com> To: git@vger.kernel.org Cc: Karthik Nayak , Patrick Steinhardt , gitster@pobox.com, peff@peff.net X-Mailer: b4 0.15-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=10017; i=karthik.188@gmail.com; h=from:subject:message-id; bh=abyBqfybBCnH7UU8keEbMrkjS2R1G1iKu6KpY6Wf2qg=; b=owJ4nAHtARL+kA0DAAoBPtWfJI5GjH8ByyZiAGgrALX6R+MjH5C5TMyXOZw9B8tFHcs9QKSl2 JXdklevZDwZHokBswQAAQoAHRYhBFfOTH9jdXEPy2XGBj7VnySORox/BQJoKwC1AAoJED7VnySO Rox/svUL/jY+LuPjmb57EqeND4HIY8XFONxsBz31aQQDlwqhmiDnnBf5dTbqZTlOIq8AQAIyJhC C6K28JqGyxN2j6PTB8J+LKEvqJw2KaMNm1y/cX1a0jxM52rSTbqUHBWkX9wwaEJRe6T8DQ9YLKb le6IvFEITpsvKFRyP0vEzJCh/QXQ3Qdh8L268iOHe6BW/1SdZpWOgKsZwkjgjGv1jUvzygjD+1c iRVKG3IcLo3gcEjJfhiDeFv/Pwg1dfmS6poEuzPwkhwVFwjgcka4dI1tZyUnLyPAFAUb76eARXQ X/qDu9itS+hyOJLUJKYQXgLTmAFEK6Lx2yXDAwTUisqMH0SjdSQ9l2GOEIR5PwXBApNmEIZg15l Wdg3/+5HYR8yqhIvF+pOlvFTHFNOd0bUnelfFdOmJlDbrUPIAk4YD36H3uk5m3Kt+lzAaFAAjh7 aUfRFyEMDkDulph7XW6KP+Wqh6ocpF2uRuMYPYhCTHcCChNxrmfngwI6x33ivza1/H5hr0ScYS5 P0= X-Developer-Key: i=karthik.188@gmail.com; a=openpgp; fpr=57CE4C7F6375710FCB65C6063ED59F248E468C7F The reference updates performed as a part of 'git-fetch(1)', take place one at a time. For each reference update, a new transaction is created and committed. This is necessary to ensure we can allow individual updates to fail without failing the entire command. The command also supports an '--atomic' mode, which uses a single transaction to update all of the references. But this mode has an all-or-nothing approach, where if a single update fails, all updates would fail. In 23fc8e4f61 (refs: implement batch reference update support, 2025-04-08), we introduced a new mechanism to batch reference updates. Under the hood, this uses a single transaction to perform a batch of reference updates, while allowing only individual updates to fail. Utilize this newly introduced batch update mechanism in 'git-fetch(1)'. This provides a significant bump in performance, especially when dealing with repositories with large number of references. Adding support for batched updates is simply modifying the flow to also create a batch update transaction in the non-atomic flow. With the reftable backend there is a 22x performance improvement, when performing 'git-fetch(1)' with 10000 refs: Benchmark 1: fetch: many refs (refformat = reftable, refcount = 10000, revision = master) Time (mean ± σ): 3.403 s ± 0.775 s [User: 1.875 s, System: 1.417 s] Range (min … max): 2.454 s … 4.529 s 10 runs Benchmark 2: fetch: many refs (refformat = reftable, refcount = 10000, revision = HEAD) Time (mean ± σ): 154.3 ms ± 17.6 ms [User: 102.5 ms, System: 56.1 ms] Range (min … max): 145.2 ms … 220.5 ms 18 runs Summary fetch: many refs (refformat = reftable, refcount = 10000, revision = HEAD) ran 22.06 ± 5.62 times faster than fetch: many refs (refformat = reftable, refcount = 10000, revision = master) In similar conditions, the files backend sees a 1.25x performance improvement: Benchmark 1: fetch: many refs (refformat = files, refcount = 10000, revision = master) Time (mean ± σ): 605.5 ms ± 9.4 ms [User: 117.8 ms, System: 483.3 ms] Range (min … max): 595.6 ms … 621.5 ms 10 runs Benchmark 2: fetch: many refs (refformat = files, refcount = 10000, revision = HEAD) Time (mean ± σ): 485.8 ms ± 4.3 ms [User: 91.1 ms, System: 396.7 ms] Range (min … max): 477.6 ms … 494.3 ms 10 runs Summary fetch: many refs (refformat = files, refcount = 10000, revision = HEAD) ran 1.25 ± 0.02 times faster than fetch: many refs (refformat = files, refcount = 10000, revision = master) With this we'll either be using a regular transaction or a batch update transaction. This helps cleanup some code which is no longer needed as we'll now always have some type of 'ref_transaction' object being propagated. One big change is that earlier, each individual update would propagate a failure. Whereas now, the `ref_transaction_for_each_rejected_update` function is called at the end of the flow to capture the exit status for 'git-fetch(1)' and also to print F/D conflict errors. This does change the order of the errors being printed, but the behavior stays the same. Since transaction errors are now explicitly defined as part of 76e760b999 (refs: introduce enum-based transaction error types, 2025-04-08), utilize them and get rid of custom errors defined within 'builtin/fetch.c'. Signed-off-by: Karthik Nayak --- builtin/fetch.c | 127 ++++++++++++++++++++++++++++++++------------------------ 1 file changed, 73 insertions(+), 54 deletions(-) diff --git a/builtin/fetch.c b/builtin/fetch.c index 5279997c96..f200194f77 100644 --- a/builtin/fetch.c +++ b/builtin/fetch.c @@ -641,9 +641,6 @@ static struct ref *get_ref_map(struct remote *remote, return ref_map; } -#define STORE_REF_ERROR_OTHER 1 -#define STORE_REF_ERROR_DF_CONFLICT 2 - static int s_update_ref(const char *action, struct ref *ref, struct ref_transaction *transaction, @@ -651,7 +648,6 @@ static int s_update_ref(const char *action, { char *msg; char *rla = getenv("GIT_REFLOG_ACTION"); - struct ref_transaction *our_transaction = NULL; struct strbuf err = STRBUF_INIT; int ret; @@ -661,43 +657,10 @@ static int s_update_ref(const char *action, rla = default_rla.buf; msg = xstrfmt("%s: %s", rla, action); - /* - * If no transaction was passed to us, we manage the transaction - * ourselves. Otherwise, we trust the caller to handle the transaction - * lifecycle. - */ - if (!transaction) { - transaction = our_transaction = ref_store_transaction_begin(get_main_ref_store(the_repository), - 0, &err); - if (!transaction) { - ret = STORE_REF_ERROR_OTHER; - goto out; - } - } - ret = ref_transaction_update(transaction, ref->name, &ref->new_oid, check_old ? &ref->old_oid : NULL, NULL, NULL, 0, msg, &err); - if (ret) { - ret = STORE_REF_ERROR_OTHER; - goto out; - } - - if (our_transaction) { - switch (ref_transaction_commit(our_transaction, &err)) { - case 0: - break; - case REF_TRANSACTION_ERROR_NAME_CONFLICT: - ret = STORE_REF_ERROR_DF_CONFLICT; - goto out; - default: - ret = STORE_REF_ERROR_OTHER; - goto out; - } - } -out: - ref_transaction_free(our_transaction); if (ret) error("%s", err.buf); strbuf_release(&err); @@ -1139,7 +1102,6 @@ N_("it took %.2f seconds to check forced updates; you can use\n" "to avoid this check\n"); static int store_updated_refs(struct display_state *display_state, - const char *remote_name, int connectivity_checked, struct ref_transaction *transaction, struct ref *ref_map, struct fetch_head *fetch_head, @@ -1277,11 +1239,6 @@ static int store_updated_refs(struct display_state *display_state, } } - if (rc & STORE_REF_ERROR_DF_CONFLICT) - error(_("some local refs could not be updated; try running\n" - " 'git remote prune %s' to remove any old, conflicting " - "branches"), remote_name); - if (advice_enabled(ADVICE_FETCH_SHOW_FORCED_UPDATES)) { if (!config->show_forced_updates) { warning(_(warn_show_forced_updates)); @@ -1366,9 +1323,8 @@ static int fetch_and_consume_refs(struct display_state *display_state, } trace2_region_enter("fetch", "consume_refs", the_repository); - ret = store_updated_refs(display_state, transport->remote->name, - connectivity_checked, transaction, ref_map, - fetch_head, config); + ret = store_updated_refs(display_state, connectivity_checked, + transaction, ref_map, fetch_head, config); trace2_region_leave("fetch", "consume_refs", the_repository); out: @@ -1688,6 +1644,36 @@ static int set_head(const struct ref *remote_refs, struct remote *remote) return result; } +struct ref_rejection_data { + int *retcode; + int conflict_msg_shown; + const char *remote_name; +}; + +static void ref_transaction_rejection_handler(const char *refname, + const struct object_id *old_oid UNUSED, + const struct object_id *new_oid UNUSED, + const char *old_target UNUSED, + const char *new_target UNUSED, + enum ref_transaction_error err, + void *cb_data) +{ + struct ref_rejection_data *data = cb_data; + + if (err == REF_TRANSACTION_ERROR_NAME_CONFLICT && !data->conflict_msg_shown) { + error(_("some local refs could not be updated; try running\n" + " 'git remote prune %s' to remove any old, conflicting " + "branches"), data->remote_name); + data->conflict_msg_shown = 1; + } else { + const char *reason = ref_transaction_error_msg(err); + + error(_("fetching ref %s failed: %s"), refname, reason); + } + + *data->retcode = 1; +} + static int do_fetch(struct transport *transport, struct refspec *rs, const struct fetch_config *config) @@ -1808,6 +1794,24 @@ static int do_fetch(struct transport *transport, retcode = 1; } + /* + * If not atomic, we can still use batched updates, which would be much + * more performant. We don't initiate the transaction before pruning, + * since pruning must be an independent step, to avoid F/D conflicts. + * + * TODO: if reference transactions gain logical conflict resolution, we + * can delete and create refs (with F/D conflicts) in the same transaction + * and this can be moved above the 'prune_refs()' block. + */ + if (!transaction) { + transaction = ref_store_transaction_begin(get_main_ref_store(the_repository), + REF_TRANSACTION_ALLOW_FAILURE, &err); + if (!transaction) { + retcode = -1; + goto cleanup; + } + } + if (fetch_and_consume_refs(&display_state, transport, transaction, ref_map, &fetch_head, config)) { retcode = 1; @@ -1839,16 +1843,31 @@ static int do_fetch(struct transport *transport, free_refs(tags_ref_map); } - if (transaction) { - if (retcode) - goto cleanup; + if (retcode) + goto cleanup; - retcode = ref_transaction_commit(transaction, &err); + retcode = ref_transaction_commit(transaction, &err); + if (retcode) { + /* + * Explicitly handle transaction cleanup to avoid + * aborting an already closed transaction. + */ + ref_transaction_free(transaction); + transaction = NULL; + goto cleanup; + } + + if (!atomic_fetch) { + struct ref_rejection_data data = { + .retcode = &retcode, + .conflict_msg_shown = 0, + .remote_name = transport->remote->name, + }; + + ref_transaction_for_each_rejected_update(transaction, + ref_transaction_rejection_handler, + &data); if (retcode) { - /* - * Explicitly handle transaction cleanup to avoid - * aborting an already closed transaction. - */ ref_transaction_free(transaction); transaction = NULL; goto cleanup; -- 2.49.0