anonymous_namespace{my_system_api_cgroup.cc} Namespace Reference

Functions
template<typename... Args>
bool	read_line_from_file (const std::string_view &path, Args &...args)
	Utility: Read the first line from the file specified in path and copy its contents into the arguments passed. More...
std::optional< std::string >	get_cgroup_path (std::string_view pattern)
	Determine which cgroup we belong to. More...
static bool	is_valid_path (const std::string_view &path)
std::optional< uint64_t >	cgroup_memory (const std::string_view &info_prefix, const std::string &mem_prefix, const std::string &mem_suffix, const bool with_root, std::function< bool(const std::string_view &)> v2_default_handler=nullptr)
	Read memory limits from cgroups. More...
uint64_t	handle_v1_memory_default (uint64_t memory)
	Determine if the cgroup v1 memory is the default value and return 0 if it is. More...
std::optional< uint64_t >	cgroup_v1_memory ()
bool	handle_v2_memory_default (const std::string_view &path)
	Identify if cgroup v2 memory is the default or if could not be determined. More...
std::optional< uint64_t >	cgroup_v2_memory ()

Variables
constexpr std::string_view	cgroup_info {"/proc/self/cgroup"}
	Path containing information about which cgroup we belong to. More...
constexpr std::string_view	v1_info_prefix {":memory:"}
	cgroup v1 pattern to extract cgroup path from cgroup_info More...
const std::string	v1_mem_prefix {"/sys/fs/cgroup/memory"}
	cgroup v1 prefix to read memory limits More...
const std::string	v1_mem_suffix {"/memory.limit_in_bytes"}
	cgroup v1 suffix to read memory limits More...
constexpr std::string_view	v2_info_prefix {"0::"}
	cgroup v2 pattern to extract cgroup path from cgroup_info More...
const std::string	v2_mem_prefix {"/sys/fs/cgroup"}
	cgroup v2 prefix to read memory limits More...
const std::string	v2_mem_suffix {"/memory.max"}
	cgroup v2 suffix to read memory limits More...

Function Documentation

cgroup_memory()

std::optional< uint64_t > anonymous_namespace{my_system_api_cgroup.cc}::cgroup_memory	(	const std::string_view &	info_prefix,
		const std::string &	mem_prefix,
		const std::string &	mem_suffix,
		const bool	with_root,
		std::function< bool(const std::string_view &)>	v2_default_handler = nullptr
	)

Read memory limits from cgroups.

This wrapper is common for both cgroup v1, v2

Parameters

[in]	info_prefix	Pattern used to extract cgroup from proc/self/cgroup
[in]	mem_prefix	cgroup path prefix to identify memory controller
[in]	mem_suffix	cgroup path suffix to identify file with memory limit
[in]	with_root	True if limits are to be read from root cgroup, false otherwise (read cgroup from info_prefix)
[in]	v2_default_handler	Function to handle default memory in cgroup v2

Returns

memory read from cgroup on success, 0 if default (unlimited), nullopt otherwise

Note

Default handler is required cgroup v2 and not v1 because as v1 writes 0 or fixed value which can still be parsed, but v2 writes string 'max' which requires special handling

cgroup_v1_memory()

std::optional< uint64_t > anonymous_namespace{my_system_api_cgroup.cc}::cgroup_v1_memory

(

)

cgroup_v2_memory()

std::optional< uint64_t > anonymous_namespace{my_system_api_cgroup.cc}::cgroup_v2_memory

(

)

get_cgroup_path()

std::optional< std::string > anonymous_namespace{my_system_api_cgroup.cc}::get_cgroup_path

(

std::string_view

pattern

)

Determine which cgroup we belong to.

This is common for cgroup v1 and v2.

Returns

path to the cgroup or std::nullopt on failure

handle_v1_memory_default()

uint64_t anonymous_namespace{my_system_api_cgroup.cc}::handle_v1_memory_default

(

uint64_t

memory

)

Determine if the cgroup v1 memory is the default value and return 0 if it is.

Return the input if it is not the default value or if the default could not be determined.

Parameters

[in]

memory

memory read from cgroup v1 paths

Returns

0 if memory value is default, input memory value otherwise

handle_v2_memory_default()

bool anonymous_namespace{my_system_api_cgroup.cc}::handle_v2_memory_default

(

const std::string_view &

path

)

Identify if cgroup v2 memory is the default or if could not be determined.

Parameters

[in]

path

Path to the memory v2 cgroup path

Returns

true if memory value is default, false otherwise

is_valid_path()

static bool anonymous_namespace{my_system_api_cgroup.cc}::is_valid_path ( const std::string_view &  path )

inlinestatic

read_line_from_file()

template<typename... Args>

bool anonymous_namespace{my_system_api_cgroup.cc}::read_line_from_file	(	const std::string_view &	path,
		Args &...	args
	)

Utility: Read the first line from the file specified in path and copy its contents into the arguments passed.

Parameters

[in]	path	Path to file
[out]	args	Pass the arguments that you expect to read from the file in the order of their appearance in the file

Returns

true if able to read and parse the file, false otherwise

Variable Documentation

cgroup_info

constexpr std::string_view anonymous_namespace{my_system_api_cgroup.cc}::cgroup_info {"/proc/self/cgroup"}

constexpr

Path containing information about which cgroup we belong to.

v1_info_prefix

constexpr std::string_view anonymous_namespace{my_system_api_cgroup.cc}::v1_info_prefix {":memory:"}

constexpr

cgroup v1 pattern to extract cgroup path from cgroup_info

v1_mem_prefix

const std::string anonymous_namespace{my_system_api_cgroup.cc}::v1_mem_prefix {"/sys/fs/cgroup/memory"}

cgroup v1 prefix to read memory limits

v1_mem_suffix

const std::string anonymous_namespace{my_system_api_cgroup.cc}::v1_mem_suffix {"/memory.limit_in_bytes"}

cgroup v1 suffix to read memory limits

v2_info_prefix

constexpr std::string_view anonymous_namespace{my_system_api_cgroup.cc}::v2_info_prefix {"0::"}

constexpr

cgroup v2 pattern to extract cgroup path from cgroup_info

v2_mem_prefix

const std::string anonymous_namespace{my_system_api_cgroup.cc}::v2_mem_prefix {"/sys/fs/cgroup"}

cgroup v2 prefix to read memory limits

v2_mem_suffix

const std::string anonymous_namespace{my_system_api_cgroup.cc}::v2_mem_suffix {"/memory.max"}

cgroup v2 suffix to read memory limits