Programming


MilliSeconds per day

To compute the number of milliseconds per day, you can use the following snippets:

Java


final long millisecondsPerDay = 24 /*hours*/ * 60 /*minutes*/ * 60 /*seconds*/ * 1000 /*milliseconds*/;

C/C++


const unsigned long millisecondsPerDay = 24 /*hours*/ * 60 /*minutes*/ * 60 /*seconds*/ * 1000 /*milliseconds*/;


Android Studio – No space left on device 10

Recently we tried to install some packages from the Android SDK through Android Studio 3.0.1 and we got the error that the PC ran out of space while downloading the necessary packages and could not perform the operation.

Full Error Log:

To install:
- Google APIs Intel x86 Atom System Image (system-images;android-27;google_apis;x86)
Preparing "Install Google APIs Intel x86 Atom System Image (revision: 2)".
Downloading https://dl.google.com/android/repository/sys-img/google_apis/x86-27_r02.zip
An error occurred while preparing SDK package Google APIs Intel x86 Atom System Image: Cannot download 'https://dl.google.com/android/repository/sys-img/google_apis/x86-27_r02.zip': No space left on device
, response: 200 OK.
"Install Google APIs Intel x86 Atom System Image (revision: 2)" failed.
Failed packages:
- Google APIs Intel x86 Atom System Image (system-images;android-27;google_apis;x86)

Although the disk had a lot of free space, we got this error because the /tmp partition on our GNU/Linux Fedora 27 workstation was too small (~4GB).

$ df -h;
Filesystem Size Used Avail Use% Mounted on
devtmpfs 3.9G 0 3.9G 0% /dev
tmpfs 3.9G 107M 3.8G 3% /dev/shm
tmpfs 3.9G 1.9M 3.9G 1% /run
tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
/dev/mapper/fedora-root 50G 35G 12G 75% /
tmpfs 3.9G 2.1M 3.9G 1% /tmp
/dev/sdb1 477M 179M 269M 41% /boot
/dev/mapper/fedora-home 178G 37G 132G 22% /home
tmpfs 794M 16K 794M 1% /run/user/42
tmpfs 794M 9.2M 785M 2% /run/user/1000

/tmp was not explicitly set so it was automatically configured to have half of the size of the RAM.
We didn’t not want to change the download path for the Java environment (and hence Android Studio and Android SDK tools) as after leaving the tmpfs folder it could mean that we would have to manually maintain the new path and clean it up. So we ended up in temporarily increasing the size of /tmp partition which did the trick and the virtual device was installed successfully.

Solution – temporarily increase the size of the /tmp partition:

The command we used to increase the size of the /tmp partition on Fedora 27 was the following:


sudo mount -o remount,size=8G,noatime /tmp;

After executing we, it we immediately saw that the results were applied without the need for a restart or any other operation and we could proceed to use the PC as normal.

$ df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 3.9G 0 3.9G 0% /dev
tmpfs 3.9G 89M 3.8G 3% /dev/shm
tmpfs 3.9G 1.9M 3.9G 1% /run
tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
/dev/mapper/fedora-root 50G 35G 12G 75% /
tmpfs 8.0G 2.0M 8.0G 1% /tmp
/dev/sdb1 477M 179M 269M 41% /boot
/dev/mapper/fedora-home 178G 37G 132G 22% /home
tmpfs 794M 16K 794M 1% /run/user/42
tmpfs 794M 6.9M 787M 1% /run/user/1000

The information for tmpfs we got it from: https://wiki.archlinux.org/index.php/Tmpfs

Full Correct Execution Log:

To install:
- Google APIs Intel x86 Atom System Image (system-images;android-27;google_apis;x86)
Preparing "Install Google APIs Intel x86 Atom System Image (revision: 2)".
Downloading https://dl.google.com/android/repository/sys-img/google_apis/x86-27_r02.zip
"Install Google APIs Intel x86 Atom System Image (revision: 2)" ready.
Installing Google APIs Intel x86 Atom System Image in /home/xeirwn/Android/Sdk/system-images/android-27/google_apis/x86
"Install Google APIs Intel x86 Atom System Image (revision: 2)" complete.
"Install Google APIs Intel x86 Atom System Image (revision: 2)" finished.


Manually set the CMake output folder 1

If you want to manually set the global output folder for you whole CMake project and depending on the output you expect add the following configuration lines in the root CMakeLists.txt file of your project:

set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)

In case you wan to specify those folders per target, you can update them as follows:

set_target_properties( target_or_targets
  PROPERTIES
  ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib"
  LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib"
  RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/bin"
)

Please note that we are setting the same properties using different variables.

The CMAKE_ARCHIVE_OUTPUT_DIRECTORY variable is used to initialize the ARCHIVE_OUTPUT_DIRECTORY property on all the targets.
ARCHIVE_OUTPUT_DIRECTORY property specifies the directory into which archive target files should be built.
An archive output artifact of a buildsystem target may be:

  • The static library file (e.g. .lib or .a) of a static library target created by the add_library() command with the STATIC option.
  • On DLL platforms: the import library file (e.g. .lib) of a shared library target created by the add_library() command with the SHARED option.
  • On DLL platforms: the import library file (e.g. .lib) of an executable target created by the add_executable() command when its ENABLE_EXPORTS target property is set.

 

The CMAKE_LIBRARY_OUTPUT_DIRECTORY variable is used to initialize the LIBRARY_OUTPUT_DIRECTORY property on all the targets.
LIBRARY_OUTPUT_DIRECTORY property specifies the directory into which library target files should be built.
A library output artifact of a buildsystem target may be:
The loadable module file (e.g. .dll or .so) of a module library target created by the add_library() command with the MODULE option.
On non-DLL platforms: the shared library file (e.g. .so or .dylib) of a shared shared library target created by the add_library() command with the SHARED option.

 

The CMAKE_RUNTIME_OUTPUT_DIRECTORY variable is used to initialize the RUNTIME_OUTPUT_DIRECTORY property on all the targets.
RUNTIME_OUTPUT_DIRECTORY property specifies the directory into which runtime target files should be built.
A runtime output artifact of a buildsystem target may be:

  • The executable file (e.g. .exe) of an executable target created by the add_executable() command.
  • On DLL platforms: the executable file (e.g. .dll) of a shared library target created by the add_library() command with the SHARED option.

From: https://cmake.org/documentation/


Two ways to append a new argument to CMAKE_ARGS list for ExternalProject_Add

Recently, we wanted to pass a new cached value to an external project in CMake via the CMAKE_ARGS variable.

CMAKE_ARGS holds various types of arguments. From which, the arguments in the form -Dname:type=value are passed to the CMake command line and cannot be changed by the user.

We found two ways to add a new argument pair to the CMAKE_ARGS of the external project.

The first method uses the set function:

set(CMAKE_ARGS "${CMAKE_ARGS} -D${CACHE_VAR}${CACHE_VAR_TYPE}=\"${${CACHE_VAR}}\"")

where basically we create a new string that starts with the existing value of CMAKE_ARGS and then we append to its end the new pair.

The second method uses the list function:

list(APPEND CMAKE_ARGS "-D${CACHE_VAR}${CACHE_VAR_TYPE}=${${CACHE_VAR}}")

that treats CMAKE_ARGS as a list and it appends to its end the new pair.

To verify by hand that they were equivalent we did the following small test with success

#Copy the original value of ${CMAKE_ARGS}
set(CMAKE_ARGS_ORIGINAL ${CMAKE_ARGS})

#Define the Name, Type and Value for the new argument pairs
set(CACHE_VAR_P_NAME PRODUCTS_DIR)
set(CACHE_VAR_P_TYPE string)
set(CACHE_VAR_P_VALUE "someplace/with spaces")

set(CACHE_VAR_C_NAME CLIENTS_DIR)
set(CACHE_VAR_C_TYPE string)
set(CACHE_VAR_C_VALUE "another/place")

#Print the original value of ${CMAKE_ARGS}
MESSAGE(STATUS "CMAKE_ARGS: '" ${CMAKE_ARGS} "'")

#Append the two pairs to ${CMAKE_ARGS} using set
set(CMAKE_ARGS "${CMAKE_ARGS} -D${CACHE_VAR_P_NAME}:${CACHE_VAR_P_TYPE}=\"${CACHE_VAR_P_VALUE}\"")
set(CMAKE_ARGS "${CMAKE_ARGS} -D${CACHE_VAR_C_NAME}:${CACHE_VAR_C_TYPE}=\"${CACHE_VAR_C_VALUE}\"")

#Print the modified value of ${CMAKE_ARGS}
MESSAGE(STATUS "CMAKE_ARGS: '" ${CMAKE_ARGS} "'")

#Reset ${CMAKE_ARGS} to its original value
set(CMAKE_ARGS ${CMAKE_ARGS_ORIGINAL})

#Print the original value of ${CMAKE_ARGS} for verification
MESSAGE( STATUS "CMAKE_ARGS: '" ${CMAKE_ARGS} "'")

#Append the two pairs to ${CMAKE_ARGS} using list
list(APPEND CMAKE_ARGS "-D${CACHE_VAR_P_NAME}:${CACHE_VAR_P_TYPE}=\"${CACHE_VAR_P_VALUE}\"")
list(APPEND CMAKE_ARGS "-D${CACHE_VAR_C_NAME}:${CACHE_VAR_C_TYPE}=\"${CACHE_VAR_C_VALUE}\"")

#Print the modified value of ${CMAKE_ARGS}
#Notice that here we surrounded ${CMAKE_ARGS} with quotes so that it is printed as list of delimiter separated values
#Between each element the character ';' will be added because ${CMAKE_ARGS} is surrounded with quotes
MESSAGE(STATUS "CMAKE_ARGS: '" "${CMAKE_ARGS}" "'")

Which resulted in the following output

-- CMAKE_ARGS: ''
-- CMAKE_ARGS: ' -DPRODUCTS_DIR:string="someplace/with spaces" -DCLIENTS_DIR:string="another/place"'
-- CMAKE_ARGS: ''
-- CMAKE_ARGS: '-DPRODUCTS_DIR:string="someplace/with spaces";-DCLIENTS_DIR:string="another/place"'

From the output we can see that the two options treat the variable in a different way as using set just created a huge string containing both pairs while list created a list of two elements.
Both methods seem to work properly but we chose the list method for our external project.

The CMakeLists.txt file that we used to include the external project using custom CMAKE_ARGS resulted as follows:

cmake_minimum_required (VERSION 3.2.2)
include (ExternalProject)

set (TARGET c-banana-eat-banana)
project (${TARGET} C)

set (BANANA_ROOT ${CMAKE_CURRENT_BINARY_DIR} CACHE INTERNAL "")

#Add custom CMake arguments to be passed to the CMake command line of the external project
list(APPEND CMAKE_ARGS "-DARTIFACTS_DIR:string=\"${LIBRARIES_DIR}/${TARGET}\"")

ExternalProject_Add (${TARGET}
 URL ${CMAKE_CURRENT_SOURCE_DIR}/${TARGET}.zip
 URL URL_HASH MD5=34734a678729967f426931d913326112
 CMAKE_ARGS "${CMAKE_ARGS}"
 BUILD_IN_SOURCE 1)