diff options
Diffstat (limited to 'system/doc/design_principles')
| -rw-r--r-- | system/doc/design_principles/appup_cookbook.xml | 61 | ||||
| -rw-r--r-- | system/doc/design_principles/release_handling.xml | 52 |
2 files changed, 92 insertions, 21 deletions
diff --git a/system/doc/design_principles/appup_cookbook.xml b/system/doc/design_principles/appup_cookbook.xml index bc61578953..798b23d847 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 +603,60 @@ 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> + + <section> + <title>Emulator Upgrade from pre OTP R15</title> + <p>From OTP R15, an emulator upgrade is performed by restarting + the emulator with new versions of the core applications + (<c>kernel</c>, <c>stdlib</c> and <c>sasl</c>) before loading code + and running upgrade instruction for other applications. For this + to work, the release to upgrade from must includes OTP R15 or + later. For the case where the release to upgrade from includes an + earlier emulator version, <c>systools:make_relup</c> will create a + backwards compatible relup file. This means that all upgrade + instructions will be executed before the emulator is + restarted. The new application code will therefore be loaded into + the old emulator. If the new code is compiled with the new + emulator, there might be cases where the beam format has changed + and beam files can not be loaded. To overcome this problem, the + new code should be compiled with the old emulator.</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> |