I am reading D-Bus API Design Guidelines:
Interface files for public API should be installed to $(datadir)/dbus-1/interfaces so that other services can load them.
OK... in order to understand how these interface files work, I open the file /usr/share/dbus-1/interfaces/org.gnome.Shell.Screenshot.xml (I'm using Ubuntu 20.04)
<node>
<interface name="org.gnome.Shell.Screenshot">
...
<method name="PickColor">
<arg type="a{sv}" direction="out" name="result"/>
</method>
Well, I see the interface name, I see the method name, but that is not enough. If I want to call this method using dbus-send
$ dbus-send --print-reply --dest=<service.name> </path/to/object> org.gnome.Shell.Screenshot.PickColor
I need <service.name> and <path/to/object>, which this xml-file does not provide.
The queston is: what is the purpose of this file if it does not provide full information about the service interface? Is it used by dbus-daemon or by any other programs? Are such files really needed for something? Should I make a conclusion that an xml-file, which does not provide a path to object in , is incomplete? Should such file also mention a service known name (org.gnome.Shell.Screenshot in this case)?
The org.freedesktop.DBus.Introspectable interface has one method:
org.freedesktop.DBus.Introspectable.Introspect (out STRING xml_data)
Object instances may implement Introspect which returns an XML description of the object. The introspection format is documented at:
https://dbus.freedesktop.org/doc/dbus-specification.html#introspection-format
Using busctl on the command line I can use list to get all the services, tree to get all the objects, and then intropspect to find the API. Using these three commands I can discover the D-Bus services on a system
$ busctl list
$ busctl tree <service>
$ busctl introspect <service> <object>
The service you mentioned in your question is on the Session/User bus so it would be:
$ busctl --user list | grep Screenshot
NAME PID PROCESS USER CONNECTION UNIT SESSION DESCRIPTION
---------------------------------------------------------------------------------------------------------------------------------
org.gnome.Screenshot - - - (activatable) - - -
org.gnome.Shell.Screenshot 1259 gnome-shell LinuxMachine1 :1.37 user#1000.service - -
$ busctl --user tree org.gnome.Shell.Screenshot
├─/StatusNotifierWatcher
└─/org
├─/org/freedesktop
│ ├─/org/freedesktop/Notifications
│ └─/org/freedesktop/portal
│ └─/org/freedesktop/portal/desktop
├─/org/gnome
│ ├─/org/gnome/Mutter
│ │ ├─/org/gnome/Mutter/DisplayConfig
│ │ └─/org/gnome/Mutter/IdleMonitor
│ │ └─/org/gnome/Mutter/IdleMonitor/Core
│ ├─/org/gnome/ScreenSaver
│ ├─/org/gnome/SessionManager
│ │ └─/org/gnome/SessionManager/EndSessionDialog
│ ├─/org/gnome/Shell
│ │ ├─/org/gnome/Shell/AudioDeviceSelection
│ │ ├─/org/gnome/Shell/Introspect
│ │ ├─/org/gnome/Shell/Screencast
│ │ ├─/org/gnome/Shell/Screenshot
│ │ └─/org/gnome/Shell/Wacom
│ └─/org/gnome/keyring
│ └─/org/gnome/keyring/Prompter
└─/org/gtk
├─/org/gtk/MountOperationHandler
└─/org/gtk/Notifications
$ busctl --user introspect org.gnome.Shell.Screenshot /org/gnome/Shell/Screenshot
NAME TYPE SIGNATURE RESULT/VALUE FLAGS
org.freedesktop.DBus.Introspectable interface - - -
.Introspect method - s -
org.freedesktop.DBus.Peer interface - - -
.GetMachineId method - s -
.Ping method - - -
org.freedesktop.DBus.Properties interface - - -
.Get method ss v -
.GetAll method s a{sv} -
.Set method ssv - -
.PropertiesChanged signal sa{sv}as - -
org.gnome.Shell.Screenshot interface - - -
.FlashArea method iiii - -
.PickColor method - a{sv} -
.Screenshot method bbs bs -
.ScreenshotArea method iiiibs bs -
.ScreenshotWindow method bbbs bs -
.SelectArea method - iiii -
And for completeness, running the same command as you did:
$ busctl --user call org.gnome.Shell.Screenshot /org/gnome/Shell/Screenshot org.gnome.Shell.Screenshot PickColor
a{sv} 1 "color" (ddd) 1 1 1
The answer is in the name: it’s a D-Bus interface file. It defines an interface, not an instantiation of that interface. There may be zero or more instantiations of an interface in D-Bus, and they may be dynamic. So their paths can’t be specified in an XML file.
If D-Bus was designed now, perhaps this XML file would have been structured or implemented differently. But this is what there is.
Related
I have an issue when I'm working with NestedStack in AWS CDK, the problem is when I'm using the cdk diff command its returns the diff output return to me.
But when I have a diff inside my NestedStack it's just a reference and i really don't know what it will change inside my NestedStack.
[~] AWS::CloudFormation::Stack IAMPolicyStack.NestedStack/IAMPolicyStack.NestedStackResource IAMPolicyStackNestedStackIAMPolicyStackNestedStackResource4B98A1D2
├─ [~] NestedTemplate
│ └─ [~] .Resources:
│ └─ [~] .CDKMetadata:
│ └─ [~] .Properties:
│ └─ [~] .Analytics:
│ ├─ [-] v2:deflate64:H4sIAAAAAAAA/zPSMzLWM1BMLC/WTU7J1s3JTNKr9kstLklNCS5JTM7WcU7LC0otzi8tSk4FsZ3z81IySzLz82p1AipLMvLz9I31DA30TBSzijMzdYtK80oyc1P1giA0AJZoScZcAAAA
│ └─ [+] v2:deflate64:H4sIAAAAAAAA/zPSMzLWM1BMLC/WTU7J1s3JTNKr9kstLklNCS5JTM7WcU7LC0otzi8tSk4FsZ3z81IySzLz82p1AipLMvLz9I31LPUMjRSzijMzdYtK80oyc1P1giA0ALbtmvJcAAAA
Hope someone out there has hit the same issue as me and has a solution about how to get the diff output from NestedStack.
Updated 30/05/2022
The featuer look like its not ready yet, but its coming in the feature based my ticket here - https://github.com/aws/aws-cdk/issues/20392
This commit adds a workaround where you can run
cdk deploy --no-execute
and then view the nested stack changes in the CloudFormation change set that gets created.
Edit: Looks like this has not been merged yet as of 1.163.1, here is the open issue.
1 - There's a "Simics Training" package shown in the package manager, and a "targets\simics-user-training" and " targets\workshop-01". Where is the documentation about starting up and going through these trainings? (I assume this is different than just the normal "my-simics-project-1/documentation.html" documentation, because that documentation doesn't ever reference either of those targets in the Getting Started section)
2 - In the documentation there's a line: "The QSP-x86 package contains a legacy processor core which is used by default in the included simulated machines. To use more modern processors, the package QSP-CPU can be installed, which contains recent processor cores." How does one actually use the QSP-CPU to select a different CPU to be simulated? (Related: I see in the release notes a bunch of mentions of ICH10. Is that what the default QSP-x86 "targets\qsp-x86\firststeps.simics" is simulating? Ideally I'd like to simulate at least a PCH-based system.)
#Point 1
If you check the doc/ folder in your SImics project, you should have the lab instructions. It is a bit inconsistent that they are stand-alone PDFs, but that comes from how they are built currently. Look for nut-001 and workshop-01.
#Point 2 (and how come StackOverflow does not have heading styles? You can really use those to write nicely structured answers)
If you have installed everything, use the scripts "qsp-atom-core.simics" etc. to run the standard QSP setup but with a different type of core. For example:
> simics.bat targets\qsp-x86\qsp-client-core.simics
To see how that core is selected, open the script file. For example, to look at the client core script, first type/cat the trampoline script in the project. Then, go and open or cat or type the script file itself. For example:
C:\Users\jengblo\simics-projects\my-simics-project-5>type targets\qsp-x86\qsp-client-core.simics
# Auto-generated file. Any changes will be overwritten!
decl { substitute "C:\\Users\\jengblo\\AppData\\Local\\Programs\\Simics\\simics-qsp-cpu-6.0.1\\targets\\qsp-x86\\qsp-client-core.simics" }
run-command-file "C:\\Users\\jengblo\\AppData\\Local\\Programs\\Simics\\simics-qsp-cpu-6.0.1\\targets\\qsp-x86\\qsp-client-core.simics"
Given that trampoline, go to the actual script file:
C:\Users\jengblo\simics-projects\my-simics-project-5>type C:\\Users\\jengblo\\AppData\\Local\\Programs\\Simics\\simics-qsp-cpu-6.0.1\\targets\\qsp-x86\\qsp-client-core.simics
# In order to run this, the QSP-x86 (2096), QSP-CPU (8112) and
# QSP-Clear-Linux (4094) packages should be installed.
decl {
! Script that runs the Quick Start Platform (QSP) with a client processor core.
params from "%simics%/targets/qsp-x86/qsp-clear-linux.simics"
default cpu_comp_class = "x86-coffee-lake"
default num_cores = 4
}
run-command-file "%simics%/targets/qsp-x86/qsp-clear-linux.simics"
And note how the "cpu_comp_class" parameter is set. The way to find available such classes in a bit obscure, admittedly. In your running Simics session started from the client-core script (for example), check the types of the components inside the motherboard.
simics> list-components board.mb
┌─────────┬─────────────────────────┐
│Component│Class │
├─────────┼─────────────────────────┤
│cpu0 │processor_x86_coffee_lake│
│gpu │pci_accel_vga_comp │
│memory │simple_memory_module │
│nb │northbridge_x58 │
│sb │southbridge_ich10 │
└─────────┴─────────────────────────┘
Note the class of the cpu0 component. To find other classes from the same pattern, use the list-classes command:
simics> list-classes substr = processor_x86
The following classes are available:
┌─────────────────────────────┬──────────────────────────────┐
│ Class │ Short description │
├─────────────────────────────┼──────────────────────────────┤
│processor_x86QSP1 │N/A (module is not loaded yet)│
│processor_x86QSP2 │N/A (module is not loaded yet)│
│processor_x86_airmont │N/A (module is not loaded yet)│
│processor_x86_broadwell_xeon │N/A (module is not loaded yet)│
...
You can then build a custom script to start with a given core. Follow the pattern of "qsp-client-core.simics" as found in the installation. Copy that file into your project, and modify the core class as well as other parameters.
I have stumbled the unfortunate situation, having to be in a directory in which another directory is located:
C:\Test\[Folder with unknown name]\theFileINeed.txt
The structure mentioned above originates from a Zip-file from an external source. So i can not change the structure.
My goal is to navigate to the Directory with the unknown name, so it is my working directroy and I can execute further commands there. (Like Get-Childitem e.g.)
Is there a simple way to e.g. use the cd command to move into that directory?
I have fiddled around a bit with Resolve-Path but couldn't find a helpful solution.
Thanks in advance.
Consider this structure:
C:\TMP\TEST
├───unknowndir1
│ │ nonuniquefile.txt
│ │ uniquefile.txt
│ │
│ ├───nonuniquesubdir
│ └───uniquesubdir
└───unknowndir2
│ nonuniquefile.txt
│
└───nonuniquesubdir
You could do cd .\test\*\uniquesubdir but you can't cd .\test\*\nonuniquesubdir as you'll gen an error (...) path (...) resolved to multiple containers. The same error is even with cd .\test\*\uniquesubdir\.. as if it didn't even check for existence of uniquesubdir.
So if you want to enter unknown directory based of a file it contains, you'd have to do something like this: cd (Get-Item .\test\*\uniquefile.txt).DirectoryName.
It will fail if you use nonuniquefile.txt as it again resolves to two different directories. You could enter the first of these directories with cd (Get-Item .\test\*\nonuniquefile.txt).DirectoryName[0] if you don't care which of them you use.
Performing a select on Clickhouse, on a MergeTree table that is loaded from a KafkaEngine table via a Materialized View, a simple select shows output split in groups in the clickhouse-client:
:) select * from customersVisitors;
SELECT * FROM customersVisitors
┌────────day─┬─────────createdAt───┬──────────────────_id─┬───────────mSId─┬───────xId──┬─yId─┐
│ 2018-08-17 │ 2018-08-17 11:42:04 │ 8761310857292948227 │ DV-1811114459 │ 846817 │ 0 │
│ 2018-08-17 │ 2018-08-17 11:42:04 │ 11444873433837702032 │ DV-2164132903 │ 780066 │ 0 │
└────────────┴─────────────────────┴──────────────────────┴────────────────┴────────────┴─────┘
┌────────day─┬─────────createdAt───┬──────────────────_id─┬───────────────────mSId──┬────────xId─┬─yId─┐
│ 2018-08-17 │ 2018-08-17 10:25:11 │ 14403835623731794748 │ DV-07680633204819271839 │ 307597 │ 0 │
└────────────┴─────────────────────┴──────────────────────┴─────────────────────────┴────────────┴─────┘
3 rows in set. Elapsed: 0.013 sec.
Engine is ENGINE = MergeTree(day, (mSId, xId, day), 8192)
Why does the output appear splitted in two groups?
If I'm not mistaken, the output is split when the data came from different blocks, also often it leads to being processed in different threads. If you want to get rid of it, wrap your query in outer select
select * from (...)
MergeTree Engine is designed for faster WRITE and READ operations.
Fater writes are achieved by inserting data in parts and then the data is merged offline into a single part for faster reads.
you can see the data partition the following directory :
ls /var/lib/clickhouse/data/database_name/table_name
If you run the following query, you will find this that the data is now available in a single group and also a new partition is available at the above location :
optimize table MY_TABLE_NAME
Optimize table forces merging of partition, but in usual cases, you can just leave it on Click house .
I'm have an OID that is generating a tuple that is evidently not valid.
This is the error I get when trying to delete a table in psql after some \set VERBOSITY verbose:
delete from my_table where my_column = 'some_value';
ERROR: XX000: cache lookup failed for constraint 34055
LOCATION: ri_LoadConstraintInfo, ri_triggers.c:2832
This is what I found elsewhere.
2827 : /*
2828 : * Fetch the pg_constraint row so we can fill in the entry.
2829 : */
2830 548 : tup = SearchSysCache1(CONSTROID, ObjectIdGetDatum(constraintOid));
2831 548 : if (!HeapTupleIsValid(tup)) /* should not happen */
2832 0 : elog(ERROR, "cache lookup failed for constraint %u", constraintOid);
2833 548 : conForm = (Form_pg_constraint) GETSTRUCT(tup);
2834 :
2835 548 : if (conForm->contype != CONSTRAINT_FOREIGN) /* should not happen */
2836 0 : elog(ERROR, "constraint %u is not a foreign key constraint",
I read this means the OID is being referenced in other places. Where are these other places and does anyone know how I to clean something like this up?
I really like the /* should not happen */ comment on line 2831.
I'd say that this means that you have catalog corruption.
Foreign key constraints are internally implemented as triggers. When that trigger fires, it tries to find the constraint that belongs to it. This seems to fail in your case, and that causes the error.
You can see for yourself:
SELECT tgtype, tgisinternal, tgconstraint
FROM pg_trigger
WHERE tgrelid = 'my_table'::regclass;
┌────────┬──────────────┬──────────────┐
│ tgtype │ tgisinternal │ tgconstraint │
├────────┼──────────────┼──────────────┤
│ 5 │ t │ 34055 │
│ 17 │ t │ 34055 │
└────────┴──────────────┴──────────────┘
(2 rows)
Now try to look up that constraint:
SELECT conname
FROM pg_constraint
WHERE oid = 34055;
┌─────────┐
│ conname │
├─────────┤
└─────────┘
(0 rows)
To recover from such a corruption, you should restore your latest good backup.
You can try to salvage your data by using pg_dumpall to dump the running PostgreSQL cluster, create a new cluster and restore the dump there. If you are lucky, you now have a good copy of your cluster and you can use that. If the dump or the restore fail because of data inconsistencies, you have to use more advanced methods.
As always in case of data corruption, it is best to first stop the cluster with
pg_ctl stop -m immediate
and make a physical backup of the data directory. That way you have a copy if your salvage operation further damages the data.