Document upgrade instructions restart_new_emulator and restart_emulator

5 files changed, 123 insertions, 31 deletions

diff --git a/lib/sasl/doc/src/appup.xml b/lib/sasl/doc/src/appup.xml
index 89bcf23b5e..195f9fe1d3 100644
--- a/lib/sasl/doc/src/appup.xml
+++ b/lib/sasl/doc/src/appup.xml
@@ -319,12 +319,37 @@ point_of_no_return
     <pre>
 restart_new_emulator
     </pre>
-    <p>Shuts down the current emulator and starts a ne one. All
-      processes are terminated gracefully. The new release must still
-      be made permanent when the new emulator is up and running.
-      Otherwise, the old emulator is started in case of a emulator
-      restart. This instruction should be used when a new emulator is
-      introduced, or if a complete reboot of the system should be done.</p>
+    <p>This instruction is used when erts, kernel, stdlib or sasl is
+      upgraded. It shuts down the current emulator and starts a new
+      one. All processes are terminated gracefully, and the new
+      version of erts, kernel, stdlib and sasl are used when the
+      emulator restarts. Only one <c>restart_new_emulator</c>
+      instruction is allowed in the relup, and it shall be placed
+      first. <seealso marker="systools#make_relup/3">systools:make_relup3,4</seealso>
+      will ensure this when the relup is generated. The rest of the
+      relup script is executed after the restart as a part of the boot
+      script.</p>
+    <p>An info report will be written when the upgrade is
+      completed. To programatically find out if the upgrade is
+      complete,
+      call <seealso marker="release_handler#which_release/0">
+      release_handler:which_releases</seealso> and check if the
+      expected release has status <c>current</c>.</p>
+    <p>The new release must still be made permanent after the upgrade
+      is completed. Otherwise, the old emulator is started in case of
+      an emulator restart.</p>
+    <pre>
+restart_emulator
+    </pre>
+    <p>This instruction is similar to <c>restart_new_emulator</c>,
+      except it shall be placed at the end of the relup script. It is
+      not related to an upgrade of the emulator or the core
+      applications, but can be used by any application when a complete
+      reboot of the system is reqiured.  When generating the
+      relup, <seealso marker="systools#make_relup/3">systools:make_relup/3,4</seealso>
+      ensures that there is only one <c>restart_emulator</c>
+      instruction and that it is the last instruction of the
+      relup.</p>
   </section>
 
   <section>
diff --git a/lib/sasl/doc/src/release_handler.xml b/lib/sasl/doc/src/release_handler.xml
index 5ac0dc1acc..c625b40c9d 100644
--- a/lib/sasl/doc/src/release_handler.xml
+++ b/lib/sasl/doc/src/release_handler.xml
@@ -238,7 +238,7 @@ old        reboot_old            permanent
     </func>
     <func>
       <name>install_release(Vsn) -> {ok, OtherVsn, Descr} | {error, Reason}</name>
-      <name>install_release(Vsn, [Opt]) -> {ok, OtherVsn, Descr} | {error, Reason}</name>
+      <name>install_release(Vsn, [Opt]) -> {ok, OtherVsn, Descr} | {continue_after_restart, OtherVsn, Descr} | {error, Reason}</name>
       <fsummary>Install a release in the system.</fsummary>
       <type>
         <v>Vsn = OtherVsn = string()</v>
@@ -248,7 +248,8 @@ old        reboot_old            permanent
         <v>&nbsp;Timeout = default | infinity | int()>0</v>
         <v>&nbsp;Bool = boolean()</v>
         <v>Descr = term()</v>
-        <v>Reason = {illegal_option, Opt} | {already_installed, Vsn} | {change_appl_data, term()} | term()</v>
+        <v>Reason = {illegal_option, Opt} | {already_installed, Vsn} | {change_appl_data, term()} | {missing_base_app, OtherVsn, App} | {could_not_create_hybrid_boot, term()} | term()</v>
+	<v>App = atom()</v>
       </type>
       <desc>
         <p>Installs the specified version <c>Vsn</c> of the release.
@@ -268,6 +269,15 @@ old        reboot_old            permanent
           <c>OtherVsn</c> and <c>Descr</c> are the version
           (<c>UpFromVsn</c> or <c>Vsn</c>) and description
           (<c>Descr1</c> or <c>Descr2</c>) as specified in the script.</p>
+	  <p>If <c>{continue_after_restart,OtherVsn,Descr}</c> is
+	  returned, it means that the emulator will be restarted
+	  before the upgrade instructions are executed. This will
+	  happen if the emulator or any of the applications kernel,
+	  stdlib or sasl are updated. The new version of the emulator
+	  and these core applications will execute after the restart,
+	  but for all other applications the old versions will be
+	  started and the upgrade will be performed as normal by
+	  executing the upgrade instructions.</p>
         <p>If a recoverable error occurs, the function returns
           <c>{error,Reason}</c> and the original application
           specifications are restored. If a non-recoverable error
@@ -442,7 +452,7 @@ release_handler:set_unpacked(RelFile, [{myapp,"1.0","/home/user"},...]).
       and evaluated exactly in the same way as <c>release_handler</c>
       does.</p>
     <warning>
-      <p>These function is primarily intended for simplified testing of
+      <p>These functions are primarily intended for simplified testing
         of <c>.appup</c> files. They are not run within the context of
         the <c>release_handler</c> process. They must therefore
         <em>not</em> be used together with calls to
diff --git a/lib/sasl/src/release_handler.erl b/lib/sasl/src/release_handler.erl
index abe6d6bee6..87660db3e3 100644
--- a/lib/sasl/src/release_handler.erl
+++ b/lib/sasl/src/release_handler.erl
@@ -193,11 +193,15 @@ check_check_install_options([],Purge) ->
 %%-----------------------------------------------------------------
 %% Purpose: Executes the relup script for the specified version.
 %%          The release must be unpacked.
-%% Returns: {ok, FromVsn, Descr} | {error, Reason}
+%% Returns: {ok, FromVsn, Descr} |
+%%          {continue_after_restart, FromVsn, Descr} |
+%%          {error, Reason}
 %%          Reason = {already_installed, Vsn} |
 %%                   {bad_relup_file, RelFile} |
 %%                   {no_such_release, Vsn} |
 %%                   {no_such_from_vsn, Vsn} |
+%%                   {could_not_create_hybrid_boot,Why} |
+%%                   {missing_base_app,Vsn,App} |
 %%                   {illegal_option, Opt}} |
 %%                   exit_reason()
 %%-----------------------------------------------------------------
diff --git a/system/doc/design_principles/appup_cookbook.xml b/system/doc/design_principles/appup_cookbook.xml
index bc61578953..eebe6ba7b4 100644
--- a/system/doc/design_principles/appup_cookbook.xml
+++ b/system/doc/design_principles/appup_cookbook.xml
@@ -4,7 +4,7 @@
 <chapter>
   <header>
     <copyright>
-      <year>2003</year><year>2009</year>
+      <year>2003</year><year>2011</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -603,25 +603,42 @@ code_change(_OldVsn, State, port) ->
   </section>
 
   <section>
-    <title>Emulator Restart</title>
-    <p>If the emulator can or should be restarted, the very simple
-      <c>.relup</c> file can be created manually:</p>
+    <title>Emulator Restart and Upgrade</title>
+    <p>There are two upgrade instructions that will restart the emulator:</p>
+    <taglist>
+      <tag><c>restart_new_emulator</c></tag>
+      <item>Intended for when erts, kernel, stdlib or sasl is
+        upgraded. It is automatically added when the relup file is
+        generated by <c>systools:make_relup/3,4</c>. It is executed
+        before all other upgrade instructions. See
+        <seealso marker="release_handling#restart_new_emulator_instr">Release
+        Handling</seealso> for more information about this
+        instruction.</item>
+      <tag><c>restart_emulator</c></tag>
+      <item>Used when a restart of the emulator is required after all
+        other upgrade instructions are executed. See
+        <seealso marker="release_handling#restart_emulator_instr">Release
+        Handling</seealso> for more information about this
+        instruction.</item>
+    </taglist>
+
+    <p>If an emulator restart is necessary and no upgrade instructions
+      are needed, i.e. if the restart itself is enough for the
+      upgraded applications to start running the new versions, a very
+      simple <c>.relup</c> file can be created manually:</p>
     <code type="none">
 {"B",
  [{"A",
    [],
-   [restart_new_emulator]}],
+   [restart_emulator]}],
  [{"A",
    [],
-   [restart_new_emulator]}]
+   [restart_emulator]}]
 }.</code>
-    <p>This way, the release handler framework with automatic packing
-      and unpacking of release packages, automatic path updates etc. can
-      be used without having to specify <c>.appup</c> files.</p>
-    <p>If some transformation of persistent data, for example database
-      contents, needs to be done before installing the new release
-      version, instructions for this can be added to the <c>.relup</c>
-      file as well.</p>
+    <p>In this case, the release handler framework with automatic
+      packing and unpacking of release packages, automatic path
+      updates etc. can be used without having to specify <c>.appup</c>
+      files.</p>
   </section>
 </chapter>
 
diff --git a/system/doc/design_principles/release_handling.xml b/system/doc/design_principles/release_handling.xml
index 1d62c242c0..8ed36f3c56 100644
--- a/system/doc/design_principles/release_handling.xml
+++ b/system/doc/design_principles/release_handling.xml
@@ -4,7 +4,7 @@
 <chapter>
   <header>
     <copyright>
-      <year>2003</year><year>2009</year>
+      <year>2003</year><year>2011</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -313,18 +313,35 @@
     </section>
 
     <section>
+      <marker id="restart_new_emulator_instr"></marker>
       <title>restart_new_emulator (low-level)</title>
       <p>This instruction is used when changing to a new emulator
-        version, or if a system reboot is needed for some other reason.
-        Requires that the system is started with heart beat
+        version, or when any of the core applications kernel, stdlib
+        or sasl is upgraded. If a system reboot is needed for some
+        other reason, the <c>restart_emulator</c> instruction should
+        be used instead.</p>
+      <p>Requires that the system is started with heart beat
         monitoring, see <c>erl(1)</c> and <c>heart(3)</c>.</p>
-      <p>When the release handler encounters the instruction, it shuts
-        down the current emulator by calling <c>init:reboot()</c>, see
+      <p>The <c>restart_new_emulator</c> instruction shall always be
+        the very first instruction in a relup. If the relup is
+        generated by <c>systools:make_relup/3,4</c> this is
+        automatically ensured.</p>
+      <p>When the release handler encounters the instruction, it first
+        generates a temporary boot file, which starts the new versions
+        of the emulator and the core applications. Then it shuts down
+        the current emulator by calling <c>init:reboot()</c>, see
         <c>init(3)</c>. All processes are terminated gracefully and
         the system can then be rebooted by the heart program, using
-        the new release version. This new version must still be made
-        permanent when the new emulator is up and running. Otherwise,
-        the old version is used in case of a new system reboot.</p>
+        the temporary boot file. After the reboot, the rest of the
+        relup instructions are executed. This is done as a part of the
+        boot script.</p>
+      <p>An info report is written when the upgrade is completed. To
+        programatically find out if the upgrade is complete,
+        call <c>release_handler:which_releases/0</c> and check if the
+        expected release has status <c>current</c>.</p>
+      <p>The new version must be made permanent when the new emulator
+        is up and running. Otherwise, the old version will be used in
+        case of a new system reboot.</p>
       <p>On UNIX, the release handler tells the heart program which
         command to use to reboot the system. Note that the environment
         variable <c>HEART_COMMAND</c>, normally used by the heart
@@ -333,6 +350,25 @@
         by using the SASL configuration parameter <c>start_prg</c>, see
         <c>sasl(6)</c>.</p>
     </section>
+
+    <section>
+      <marker id="restart_emulator_instr"></marker>
+      <title>restart_emulator (low-level)</title>
+      <p>This instruction is not related to upgrades of erts or any of
+        the core applications. It can be used by any application to
+        force a restart of the emulator after all upgrade instructions
+        are executed.</p>
+      <p>There can only be one <c>restart_emulator</c> instruction in
+	a relup script, and it shall always be placed at the end. If
+	the relup is generated by <c>systools:make_relup/3,4</c> this
+	is automatically ensured.</p>
+      <p>When the release handler encounters the instruction, it shuts down
+        the emulator by calling <c>init:reboot()</c>, see
+        <c>init(3)</c>. All processes are terminated gracefully and
+        the system can then be rebooted by the heart program using the
+        new release version. No more upgrade instruction will be
+        executed after the restart.</p>
+    </section>
   </section>
 
   <section>