From patchwork Wed Feb 17 21:48:41 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Hostetler X-Patchwork-Id: 12092455 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2FE41C433E0 for ; Wed, 17 Feb 2021 21:50:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ED44F64E5F for ; Wed, 17 Feb 2021 21:50:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229459AbhBQVu0 (ORCPT ); Wed, 17 Feb 2021 16:50:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58294 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231451AbhBQVuN (ORCPT ); Wed, 17 Feb 2021 16:50:13 -0500 Received: from mail-wr1-x42a.google.com (mail-wr1-x42a.google.com [IPv6:2a00:1450:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 07C26C06178A for ; Wed, 17 Feb 2021 13:48:55 -0800 (PST) Received: by mail-wr1-x42a.google.com with SMTP id v7so18929951wrr.12 for ; Wed, 17 Feb 2021 13:48:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=message-id:in-reply-to:references:from:date:subject:fcc :content-transfer-encoding:mime-version:to:cc; bh=yOVx8B7rIEXDZ/mpDexA8Qe2BDO2imKZikCVpUgG7e8=; b=ovYnAvYGYuZ+thKYKxuWAyJWnDjprGAG1oypYAddmAktt+SEXiIy8h4qB9mpK3rnjn BcPAaWrx5fKx6mGxc7HkGCfH5uqfdJnzH2nsqhcHz8+wRyM1gx8T7fqtqfK9kb1cPSJe sdyUwyPDh7QUCEZ6Gtd8U84npxsQmzSNesJGwIZeLvSYoHUeQMGsQ9+MZVik8/oBDyuO PtL13DQ2sgL8ZRusiNn/U4cO3U0P4wWJl9Oi7mklSufLPxR9xOVSPtfcEFzfsYFBcD63 mF71ysxpwWSic63OEDMcOH84RwNzsi3TyB1/NzFmvPfPLXKiH/nk3lxeH55DD/RwfuVZ zpcg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:in-reply-to:references:from:date :subject:fcc:content-transfer-encoding:mime-version:to:cc; bh=yOVx8B7rIEXDZ/mpDexA8Qe2BDO2imKZikCVpUgG7e8=; b=W4cZMUIYgo0TD49o/h/eNY162BfWVDDggPxXNiMtms3BwUP4gicibREZNfF1jV21j2 k0gxJ1cEmU7sOH6NpNlcxNRKUVCNKT9fFR9X4YRbGiStjQ9by7bDyAF43ZGsCDf9oyjH D+XFUrdPI5Eg6EqSNa9HlV3vhBcpz+VC1qqB1jgPjGXg5V+dx/TgtXj0gxeZK1Gx4sRG 9knkwP7V2bHUIhNtWFM4VhlfgioAOvQtNix90nX5zAcSQV01qV4k3s7UrO2QUB7r9wxN ExeUFHjsiOvrStxGV0yFAWODxcxNjXzX1B9+gqH2LIC8owCf5K/8sl3QOvrrYO9uo4EZ Ei6A== X-Gm-Message-State: AOAM533Di7MgBAbxFR0trMHQBRUOAC6VymWlWvgTUw1ApE/aw1eTvSUg rNHRkhuxeCWsYSqRAXs6OhVeZFY8y4g= X-Google-Smtp-Source: ABdhPJyglrAwzEPpdh3XkbwarbHJ8dWwbEFlkpFZgaA07cjoZVA6wBaK2qOMsVzaUbMwXiTneyu0+g== X-Received: by 2002:a5d:6148:: with SMTP id y8mr1154224wrt.238.1613598533780; Wed, 17 Feb 2021 13:48:53 -0800 (PST) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id e16sm7468267wrt.36.2021.02.17.13.48.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Feb 2021 13:48:53 -0800 (PST) Message-Id: <22eec60761a88107b2e337ce13eed1020352aa73.1613598529.git.gitgitgadget@gmail.com> In-Reply-To: References: Date: Wed, 17 Feb 2021 21:48:41 +0000 Subject: [PATCH v4 05/12] simple-ipc: design documentation for new IPC mechanism Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Jeff Hostetler , Jeff King , SZEDER =?utf-8?b?R8OhYm9y?= , Johannes Schindelin , Jeff Hostetler , Jeff Hostetler Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Jeff Hostetler From: Jeff Hostetler Brief design documentation for new IPC mechanism allowing foreground Git client to talk with an existing daemon process at a known location using a named pipe or unix domain socket. Signed-off-by: Johannes Schindelin Signed-off-by: Jeff Hostetler --- Documentation/technical/api-simple-ipc.txt | 34 ++++++++++++++++++++++ 1 file changed, 34 insertions(+) create mode 100644 Documentation/technical/api-simple-ipc.txt diff --git a/Documentation/technical/api-simple-ipc.txt b/Documentation/technical/api-simple-ipc.txt new file mode 100644 index 000000000000..670a5c163e39 --- /dev/null +++ b/Documentation/technical/api-simple-ipc.txt @@ -0,0 +1,34 @@ +simple-ipc API +============== + +The simple-ipc API is used to send an IPC message and response between +a (presumably) foreground Git client process to a background server or +daemon process. The server process must already be running. Multiple +client processes can simultaneously communicate with the server +process. + +Communication occurs over a named pipe on Windows and a Unix domain +socket on other platforms. Clients and the server rendezvous at a +previously agreed-to application-specific pathname (which is outside +the scope of this design). + +This IPC mechanism differs from the existing `sub-process.c` model +(Documentation/technical/long-running-process-protocol.txt) and used +by applications like Git-LFS. In the simple-ipc model the server is +assumed to be a very long-running system service. In contrast, in the +LFS-style sub-process model the helper is started with the foreground +process and exits when the foreground process terminates. + +How the simple-ipc server is started is also outside the scope of the +IPC mechanism. For example, the server might be started during +maintenance operations. + +The IPC protocol consists of a single request message from the client and +an optional request message from the server. For simplicity, pkt-line +routines are used to hide chunking and buffering concerns. Each side +terminates their message with a flush packet. +(Documentation/technical/protocol-common.txt) + +The actual format of the client and server messages is application +specific. The IPC layer transmits and receives an opaque buffer without +any concern for the content within.