y_browseremulation.c File Reference

Code for supporting (more) realistic browser emulation. More...

#include "y_core.c"
#include "y_string.c"

Go to the source code of this file.

Data Structures
struct	y_browser
	Internal browser structure, describing a browser as an entity. More...

Macros
#define	MAX_BROWSER_LIST_LENGTH   1000
	Limit the browser list to 1000 browsers, as a failsafe in case of wrong parameter settings (which may cause endless loops otherwise) More...

Functions
void	y_log_browser (const y_browser *browser)
	Log the content of a browser object. More...
void	y_save_browser_to_parameters (const y_browser *browser)
	Save the contents of a browser struct as a series of "browser_*" loadrunner parameters. More...
int	y_setup_browser_emulation_from_parameters (const char *browser_name_param, const char *browser_chance_param, const char *browser_max_connections_per_host_param, const char *browser_max_connections_param, const char *browser_user_agent_string_param)
	Initialize the browser list based on a set of prepared parameters. More...
int	y_setup_browser_emulation ()
	Initialize the browser list, using the default values for the parameter names: More...
int	y_setup_browser_emulation_from_file (char *filename)
	Initialize the browser list based on a tab-seperated CSV file. More...
y_browser *	y_choose_browser_from_list (y_browser *browser_list_head, int browser_list_chance_total)
	Choose a browser profile from a browser list at random using the defined weights in that list. More...
y_browser *	y_choose_browser ()
	Choose a browser profile from the browser list at random using the defined weights. More...
int	y_emulate_browser (y_browser *new_browser)
	Emulate a specific browser. More...

Variables
y_browser *	y_browser_list_head = NULL
	The first element in the browser list. More...
int	y_browser_list_chance_total = 0
	The total of all the browser weights added together. More...

Detailed Description

Code for supporting (more) realistic browser emulation.

Basic concept: The tester defines a list of browsers that contains:

1. browser name
2. browser chance - A weight determining the odds that said browser will be chosen. Can be a percentage, or a count from a production access log.
3. max connections - How many connections said browser uses (See: www.browserscope.org for what this value should be for your browser)
4. max connections per host - Same as above, but this setting limits the number of connections to a single hostname.
5. User agent string - A user agent string used by said browser.

This list is read in during vuser_init() to construct a list of browsers, which can then be used during the loadtest to dynamically choose a browser from the list.

Usage:

1. Set up the appropriate parameters
2. Add this file to your script, plus any supporting ylib files.
3. Add an include statement: '#include "y_browseremulation.c' to the top of vuser_init()

4. Call y_setup_browser_emulation() (or one of the alternative variants) in vuser_init()

   Example:

   vuser_init()
   {
       y_log_turn_off(); // Suppress the logging - the setup code can create a fair amount of (harmless) log messages.
       y_setup_browser_emulation();
       y_log_restore();  // Resume logging.
   }

5. Call y_choose_browser() and y_emulate_browser() at the start of each iteration.

   Example:

   Action()
   {
       // This will set up some connection options for emulating different browser versions in a realistic fashion
       {
           // Note: This will blow up if the setup code hasn't been called beforehand.
           y_browser* browser = y_choose_browser();
           y_emulate_browser(browser);
       }
   
       // .. more code ..
   }

Author

Floris Kraak

Definition in file y_browseremulation.c.

Macro Definition Documentation

#define MAX_BROWSER_LIST_LENGTH   1000

Limit the browser list to 1000 browsers, as a failsafe in case of wrong parameter settings (which may cause endless loops otherwise)

Definition at line 104 of file y_browseremulation.c.

Function Documentation

y_browser* y_choose_browser

(

)

Choose a browser profile from the browser list at random using the defined weights.

This wrapper around y_choose_browser_from_list() uses the list pointed to by y_browser_list_head to choose from.

Returns

a pointer to a randomly chosen struct browser, or NULL in case of errors.

Example:

// This will set up some connection options for emulating different browser versions in a realistic fashion
{
    // Note: This will blow up if the setup code hasn't been called beforehand.
    y_browser* browser = y_choose_browser();
    y_emulate_browser(browser);
}

See also

y_choose_browser_from_list(), y_setup_browser_emulation_from_file(), y_setup_browser_emulation_from_parameters(), y_browseremulation.c, y_browser_list_head

Author

Floris Kraak

Definition at line 558 of file y_browseremulation.c.

y_browser* y_choose_browser_from_list	(	y_browser *	browser_list_head,
		int	browser_list_chance_total
	)

Choose a browser profile from a browser list at random using the defined weights in that list.

Parameters

[in]	browser_list_head	The first entry of a previously constructed single-linked browser list.
[in]	browser_list_chance_total	The total of the browser weights in the list.

Returns

a pointer to a randomly chosen struct browser, or NULL in case of errors.

Example:

// This will set up some connection options for emulating different browser versions in a realistic fashion
{
    // Note: This will blow up if the setup code hasn't been called beforehand.
    y_browser* browser = y_choose_browser_from_list(y_browser_list_head, y_browser_list_chance_total);
    y_emulate_browser(browser);
}

Note

In most cases a call to the y_choose_browser() wrapper should suffice, instead.

See also

y_choose_browser(), y_setup_browser_emulation_from_file(), y_setup_browser_emulation_from_parameters(), y_browseremulation.c, y_browser_list_head

Author

Floris Kraak

Definition at line 484 of file y_browseremulation.c.

int y_emulate_browser

(

y_browser *

new_browser

)

Emulate a specific browser.

This will set up the MAX_TOTAL_CONNECTIONS, MAX_CONNECTIONS_PER_HOST socket options and user_agent_string settings for the browser listed.

Example:

// This will set up some connection options for emulating different browser versions in a realistic fashion
{
    // Note: This will blow up if the setup code hasn't been called beforehand.
    y_browser* browser = y_choose_browser();
    y_emulate_browser(browser);
}

See also

y_choose_browser, y_choose_browser_from_list, y_browser_emulation.c, web_set_sockets_option(), web_add_auto_header()

Parameters

[in]

new_browser

Pointer to a browser struct for the browser to be emulated.

Returns

0 if no errors occurred, -1 in case of an error.

Author

Floris Kraak

Definition at line 583 of file y_browseremulation.c.

void y_log_browser

(

const y_browser *

browser

)

Log the content of a browser object.

Given a pointer to a browser struct, log what said browser struct contains. This is useful for debugging.

Note

Passing in NULL will result in a call to lr_abort().

Parameters

[in]

browser

A pointer to the browser struct to log.

Author

Floris Kraak

Definition at line 122 of file y_browseremulation.c.

void y_save_browser_to_parameters

(

const y_browser *

browser

)

Save the contents of a browser struct as a series of "browser_*" loadrunner parameters.

This will create the following set of parameters from the browser object:

• browser_name
• browser_chance
• browser_max_connections_per_host
• browser_max_connections
• browser_user_agent_string

Parameters

[in]

browser

A pointer to the browser to create parameters for.

Note

y_emulate_browser will use this, so these parameters will contain details about what browser the script is currently emulating after that call.

Passing in NULL will result in a call to lr_abort().

Author

Floris Kraak

Definition at line 154 of file y_browseremulation.c.

int y_setup_browser_emulation

(

)

Initialize the browser list, using the default values for the parameter names:

• browser_name_param = browser_name
• browser_chance_param = browser_chance
• browser_max_connections_per_host_param = browser_max_connections_per_host
• browser_max_connections_param = browser_max_connections
• browser_user_agent_string_param = browser_user_agent_string

Example:

vuser_init()
{
    y_log_turn_off(); // Suppress the logging - the setup code can create a fair amount of (harmless) log messages.
    y_setup_browser_emulation_from_parameters("browser_name", "browser_chance", "browser_max_connections_per_host", "browser_max_connections", "browser_user_agent_string");
    y_log_restore();  // Resume logging.
}

Note

We may remove this in favor of a call to y_setup_browser_emulation_from_file() at some point.

See also

y_setup_browser_emulation_from_parameters(), y_setup_browser_emulation_from_file(), y_browseremulation.c

Author

Floris Kraak

Definition at line 328 of file y_browseremulation.c.

int y_setup_browser_emulation_from_file

(

char *

filename

)

Initialize the browser list based on a tab-seperated CSV file.

This will initialize the single-linked list of browsers, using a text file containing on each line one browser with the following fields, seperated by tabs:

1. browser name
2. chance (weight)
3. max_connections
4. max_connections_per_host
5. user_agent

The order of the fields is important; They should be listed on each line in the above order.

Note

The file should not contain headers of any kind, nor the string "END" as y_setup_browser_emulation_from_parameters() requires.

Example:

vuser_init()
{
    y_log_turn_off(); // Suppress the logging - the setup code can create a fair amount of (harmless) log messages.
    y_setup_browser_emulation_from_file("browser.dat");
    y_log_restore();  // Resume logging.
}

Note

Empty lines and comments (text starting with "#") will be ignored.

Call this during vuser_init().

Parameters

[in]

filename

The name of the file to read.

Returns

0 if setup was successful, -1 in case of an error.

See also

y_setup_browser_emulation_from_parameters()

y_browser_list_head

y_browser_list_chance_total

y_browseremulation.c

Note

You may wish to temporarily disable logging for this call using y_log_turn_off() and y_log_restore().

Author

Floris Kraak

Definition at line 371 of file y_browseremulation.c.

int y_setup_browser_emulation_from_parameters	(	const char *	browser_name_param,
		const char *	browser_chance_param,
		const char *	browser_max_connections_per_host_param,
		const char *	browser_max_connections_param,
		const char *	browser_user_agent_string_param
	)

Initialize the browser list based on a set of prepared parameters.

This will initialize the single-linked list of browsers, using the given set of parameters. The 'browser_name' parameter named here is expected to be set to "Select Next Row: Sequential", and "Update value on: Each iteration". The -last- browser name in the list has to contain the value "END" to mark the end of the list. All other parameters should be set to "Select Next Row: Same line as {browser_name_param}".

Call this during vuser_init().

Parameters

[in]	browser_name_param	Browser name. Set this parameter to "Select Next Row: Sequential", and "Update value on: Each iteration". The last browser name should be "END".
[in]	browser_chance_param	Browser weight. Can be any number as long as the total of chances does not exceed Y_RAND_MAX. Set this parameter to "Select Next Row: Same line as {browser_name_param}".
[in]	browser_max_connections_per_host_param	Maximum number of connections this browser allows per host. See www.browserscope.org for possible values. Set this parameter to "Select Next Row: Same line as {browser_name_param}".
[in]	browser_max_connections_param	Maximum number of connections this browser allows. See www.browserscope.org for possible values. Set this parameter to "Select Next Row: Same line as {browser_name_param}".
[in]	browser_user_agent_string_param	The user agent string this browser reports to the server. See your production HTTP access logs for examples. Set this parameter to "Select Next Row: Same line as {browser_name_param}".

Returns

0 if successful, -1 if errors occurred during setup.

Example:

vuser_init()
{
    y_log_turn_off(); // Suppress the logging - the setup code can create a fair amount of (harmless) log messages.
    y_setup_browser_emulation_from_parameters("browser_name", "browser_chance", "browser_max_connections_per_host", "browser_max_connections", "browser_user_agent_string");
    y_log_restore();  // Resume logging.
}

See also

y_setup_browser_emulation_from_file()

y_browser_list_head

y_browser_list_chance_total

y_browseremulation.c

Note

You may wish to temporarily disable logging here using y_log_turn_off() and y_log_restore().

Author

Floris Kraak

Definition at line 210 of file y_browseremulation.c.

Variable Documentation

int y_browser_list_chance_total = 0

The total of all the browser weights added together.

Definition at line 110 of file y_browseremulation.c.

y_browser* y_browser_list_head = NULL

The first element in the browser list.

Definition at line 107 of file y_browseremulation.c.