Event pools usage

docs/generators/generatorso2.md

@@ -92,6 +92,7 @@ This reads primaries to be transported from an MC kinematics file. Such a file i
 ```bash
 o2-sim -g extkinO2 --extKinFile <path/to/o2sim_Kine.root>
 ```
+Alien paths are compatible as well, provided they follow the syntax `alien:///path/to/file.root`. They will be opened on-the-fly, without the need to download them locally, however you might experience longer simulation times due to the remote source.
 
 ### hepmc
 

docs/o2dpgworkflow/README.md

@@ -47,6 +47,14 @@ Simulations run from a workflow are done in units of timeframes and the number o
 
 By default, the workflow description is written to `workflow.json`.
 
+### Event pools
+
+The flag `--make-evtpool` can be used to generate a workflow for event pools creation.
+```bash
+${O2DPG_ROOT}/MC/bin/o2dpg_sim_workflow.py -gen <generator> -eCM <emc energy  [GeV]> -tf <nTFs> --ns <nEvents> --make-evtpool
+```
+This will skip all the steps after signal generation (no transport), forcing the beam-spot vertex to kNoVertex and including a final step called `poolmerge` which will be used for merging all the Kine.root files generated for the `nTFs` timeframes in a `evtpool.root` file.
+
 ### Embedding
 
 The workflow can also be created for a simulation where signal type events are embedded into a certain type of background events. To enable this feature, pass the flag `--embedding`. For the background events there are the following arguments
@@ -73,6 +81,23 @@ The runner tries to execute as many tasks in parallel as possible. So while in t
 
 Often what you might want to do is running the full chain to obtain final `AO2D.root`. To achieve this and to not run tasks that are not needed, pass `-tt aod`.
 
+### Event pools usage
+
+Some guidelines must be followed when using event pools, in particular when creating an event cache the workflow runner must be set to reach the poolmerge step, such as:
+```bash
+${O2DPG_ROOT}/MC/bin/o2dpg_workflow_runner.py -f workflow.json -tt pool
+```
+Instead, when feeding the pool to an O2DPG workflow (using `extkinO2` as generator) the user must be aware that by default the events will be randomised (with the same seed used in each timeframe), while phi randomisation is not active.
+An example on how to run a workflow including the phi angle random rotation would look like this:
+```bash
+${O2DPG_ROOT}/MC/bin/o2dpg_sim_workflow.py -eCM <emc energy  [GeV]> -gen extkinO2 -tf <nTFs> --ns <nEvents>
+                                           -confKey "GeneratorFromO2Kine.randomphi=true;GeneratorFromO2Kine.fileName=/path/to/file/filename.root"
+                                           -gen extkinO2 -interactionRate 500000
+# Followed by
+${O2DPG_ROOT}/MC/bin/o2dpg_workflow_runner.py -f workflow.json -tt aod
+```
+If the randomisation of events needs to be removed, the user can do it by editing manually the JSON file. A full example on event pools is provided in the [${O2DPG_ROOT}/MC/run/examples/event_pool.sh](https://github.com/AliceO2Group/O2DPG/blob/master/MC/run/examples/event_pool.sh) script (call the `--help` flag or check the source for usage information).
+
 ### About finished tasks
 
 Once a task is done, it will never be repeated unless you delete the `<task_name>_log_done` in the directory. Remove that file and run again.

docs/o2dpgworkflow/anchored.md

@@ -1,5 +1,5 @@
 ---
-sort: 2
+sort: 1
 title: Anchored MC
 ---
 

docs/o2dpgworkflow/ccdb.md

@@ -1,5 +1,5 @@
 ---
-sort: 3
+sort: 2
 title: CCDB
 ---