Let's all help the police!

A day ago there was a "leak" of three TV series pilots. I know, it sounds like someone out there is pissing TV series, but a look at most of them and you start seeing the truth of it. I don't really believe they were stolen or anything, either. I think they were deliberately distributed to gauge viewer reaction. The three shows in question are Blindspot, Lucifer and Minority Report. What do they all have in common? Law enforcement. It gets ridiculous from here on, you've been warned.

Blindspot is about a young woman (lovely Jaimie Alexander - the actress playing the Asgardian warrior Lady Sif in the Thor Marvel universe) found naked, without memories and tattooed all over her body. The tattoos are clues about future crimes and our Jane Doe helps the FBI solve them. The series has the obvious hallmarks of the post Lost era, with just enough artificial mystery to keep one guessing, but not really caring. Anyway, all I can say is that if you make a show about Jaimie Alexander found naked you should bloody show her naked! Stupid Americans! The French should start remaking these shows and demonstrate how it is done!

Lucifer is about... the devil. He comes to Earth because he got tired of ruling Hell - which was his divine punishment from his father, God. And by Earth I mean Los Angeles. Yes, very subtle. He teams up with another lovely (Lauren German) who is a police detective. Why, you might ask? Devil may care, he just loves solving crimes and has daddy issues. The show is so ridiculously pompous that it raises hackles. It reminds me of the well deservedly cancelled The Transporter series.

Minority Report is based on a movie about "precogs" used to stop crime by predicting it, leading to the paradox of arresting and incarcerating people because of crimes they did not commit. Yet. I haven't watched it. Yet. But since the movie was based itself on the works of famous paranoid sci-fi writer Phillip K. Dick, it is the only one that I have hopes for. Of course the detective will be a young attractive person, teamed with another young attractive person with some special power that helps solving some type of crisis, probably crimes and possibly related to terror attacks. I can see it... in the future...

Update: I was right. One of the precogs in the movie helps a young black female police detective to prevent crimes. This is a horrible perversion of the film, which ended with showing the precog system not working and putting innocent people in jail. In the series, the police is frustrated that the precog era has ended and is convinced that every released arrestee from the program would have become a killer. Yuck!

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Star Trek Prime Directive, by Judith and Garfield Reeves Stevens

Another great Star Trek novel placed in the Kirk era, Star Trek Prime Directive keeps the reader/listener on the edge of their seat. It starts with a disgraced Kirk, a scattered crew and a scrapped Enterprise. It shows the dark, bureaucratic side of the Federation, cruel and merciless when you are not the lucky wearer of the golden captain uniform or, even better, an admiral. How did it come to this? The answer is both captivating, original and with deep roots in the Star Trek basic tenant: the Prime Directive.

I actually listened to the audiobook, also on YouTube (see embedded video), which was very well narrated. If I had any problems with the story was that it was clearly very biased. Kirk is always thinking of the poor alien species that are like humans, but seems to have no qualms to experiment with phaser fire and even slightly torture other alien beings if they are bug like. Also Spock seems very little a Vulcan in this.

Bottom line is that the idea was intriguing and original and the style of the writing was very good. One of the best ST novels so far.

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LoggerEventSource error: Not enough storage is available to complete this operation

I've come upon this strange Not enough storage is available to complete this operation ArgumentException when creating an instance of EventSource derived classes. This class is responsible for creating entries in Windows logs. Strangely enough, there are very few articles on the Internet connecting the class with this particular exception, so I started to investigate. One important thing to notice is that the exception is intermittent. Basically you can cycle a few times with a try/catch block and get a valid instance. That seems to indicate some sort of race condition. So far, this is the easy solution I could find. However, I really wanted to know why does it happen.

If I remove the EventSource class from the searches I get more pages reporting the same exception and one of the reasons that people say it happens is related to the size of the registry. Retrospectively it makes sense, but it never occurred to me that the system registry has a maximum size. But is that the problem? Looking with the EventViewer summary I see something like this:

Of course, the most obvious thing there is the exact size of each log category: 20.00 MB. If one right-clicks on any of the log groups and goes to Properties, the size limit for each is clearly shown and configurable. So is that the problem?

The exception is thrown almost exclusively when the logging is heavy: multiple threads trying to log stuff at the same time. Since retrying usually solves the problem, my guess is that the exception is thrown somewhere between the request for a new log entry and the process that eliminates old entries to allow for new ones. Unfortunately I don't see any configuration option for how many entries to eliminate. I would have liked to clear, let's say, 20% of the log when it is full to make this problem less relevant. Perhaps hidden in the bowels of the system registry there is a way to set this, but at this time I don't know it. Nor is it clear if I have the option to remove more of the less important events rather than just the oldest. Clearly the EventLog class in .NET supports deleting individual log entries, so this is feasible if it ever becomes a real problem.

So far, my solution is to just try again when the error is thrown:

LoggerEventSource eventSource = null; //EventSource derived class (see documentation)
for (var i = 0; i < 5 && eventSource == null; i++)
{
    try
    {
        eventSource = new LoggerEventSource();
    }
    catch (ArgumentException)
    {
        Thread.Sleep(100);
    }
}

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Star Trek: Strangers from the Sky

Star Trek: Strangers from the Sky is an audiobook read by George Takei and Leonard Nimoy. While it is a typical ST The Original Series plot, with god like aliens, travel back in time to significant moments of Earth's history and a focus on high moral values that, in the end, save the day, I felt that it was a little bit more subtle, deeper than a typical episode of any of the series. Was it because of the introspection of the characters, or the wonderful narration of Nimoy and Takei, I do not know. What I can say is that I enjoyed listening to the story quite a lot and I recommend it highly for any Star Trek fan.

I also don't know if it is in the public domain or not, all I can say is that I listened to it on YouTube and so can you:
Of course you cannot listen to it on YouTube anymore. Some lawyers saw to that.

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Gnome Man's Land (Tim Desmond Book 1), by Esther M. Friesner

This is the third writing of Esther Friesner that I've read, after The Shunned Trailer and Druid's Blood, both excellent and funny, combining fantasy elements with the present or other realistic historical settings. Gnome Man's Land does the same thing, but I have to say I didn't find it as funny or as good as the others I mentioned. I also attempted to start Here Be Demons, another of her books, but couldn't really enjoy it enough to go past the first chapter. Probably she is one of those authors who, when they are good are really good and when they are not, well...

The book is the first of a trilogy starring Tim Desmond, a young boy of Irish descent who finds himself in a strange situation when the veil between our world and the land of the fey is punctured and more and more fantastic creatures go through. They come and attach themselves to mortals, as many of them are creatures who's very reason for existing is serving their masters. Stuff like banshees, Mongolian ancestors, goblins, kobolds, Greek demigodesses, Russian bath spirits, sprites, elves and so on and so on just sprout from the rupture, bringing annoyance and confusion more than anything. Tim somehow gets tricked into becoming the champion of the Fey on Earth and he does the job mainly because he feels all of these supernatural creatures need his help (plus the girl he secretly loves supports this and his banshee is a hot redhead to boot).

Some hilarity ensues, but often feeling a bit artificial, while the actions of the characters involved are simplistic, inconsistent and dragging on, like the author wanted to tell a joke and she ended up writing an entire book. The crises are not that good either, oscillating between childishly funny and dead bloody serious. The ending was disappointing as well, leaving a very traumatic event just in the wind, like an afterthought, pending Tim's recovery of some of his memory. I really wanted to like the book, too, but in the end I just forced myself to reach the end and I am confident I will not read the other two books in the series. I have some hopes for the Princesses series, which I understand is one of Friesner's better works.

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Change Data Capture: yes, there are enough parameters for the get_all_changes function

Change Data Capture is a useful mechanism for tracking data changes in Microsoft SQL Server. Once you enable it for a database and some of its tables, it will create a record of any change to the data of those tables. In order to use the captured data, Microsoft recommends using the table functions provided by the mechanism, mainly [cdc].[fn_cdc_get_all_changes_dbo_<table name>] and [cdc].[fn_cdc_get_net_changes_<table name>]. However, when you use them, your very first experience might be an error that looks like this: Msg 313, Level 16, State 3, Line 20 An insufficient number of arguments were supplied for the procedure or function cdc.fn_cdc_get_all_changes_ ... . Since this is an error message everyone associates with missing a parameter for a function, one might assume that the documentation is wrong and one must add another parameter. You try adding a bogus one and you get Msg 8144, Level 16, State 3, Line 9 Procedure or function cdc.fn_cdc_get_all_changes_dbo_<table name> has too many arguments specified. which brings confusion. One hint is that if we use one less parameter than in the documentation, the error is slightly different Msg 313, Level 16, State 3, Line 9 An insufficient number of arguments were supplied for the procedure or function cdc.fn_cdc_get_all_changes_dbo_<table name>. In this error message, the tracked table name is specified in the function name, as opposed to the other where ... is used instead. What is going on?

The documentation for the function (which, as usual, nobody reads past the usage syntax and the code examples - just read the Remarks section) says this: If the specified LSN range does not fall within the change tracking timeline for the capture instance, the function returns error 208 ("An insufficient number of arguments were supplied for the procedure or function cdc.fn_cdc_get_all_changes.")., which of course is the explanation for this weird behaviour, but why and when does it happen?

The why comes from a Microsoft Connect page where an overly honest developer explains that the reason for the obscure error message is the antiquated error and function system used in T-SQL: The issue here is the inability to do raiseerror from within a function that prevents us from bubbling up meaningful error message. If one looks at the source of cdc.fn_cdc_get_all_changes_dbo_<table name>, one sees that the error is thrown from another function, a system one, called [sys].[fn_cdc_check_parameters]. Doing a select on it we get the same original error which is now slightly humourous, since it comes from a completely different function than the one in the message. Since it is a system function this time, there is no source code for it.

The when is more tricky and it shows that they didn't think this through much. First of all, whenever you send a NULL or an empty (0x0000...) value to the function as the begin or end LSN you get this error message. The code examples from Microsoft always show these mysterious LSN values being received from functions like sys.fn_cdc_get_min_lsn('<schema name>_<table name>'), sys.fn_cdc_get_max_lsn(), sys.fn_cdc_map_time_to_lsn('largest less than or equal', GETDATE()) and so on, but they are hardly easy to understand, as they return an empty value for wrong parameters. For example, a common reason why your code fails is from getting the LSN like this: sys.fn_cdc_get_min_lsn('MyWonderfulTable') when in fact you need to use the schema in the name as well: sys.fn_cdc_get_min_lsn('dbo_MyWonderfulTable'). You have to use this syntax everywhere. Funny enough, if the tracked table is empty, you get the lowest LSN for the entire database, but if you use a wrong database name (or without the schema, or NULL, etc) you get an empty LSN. How an empty LSN is not the minimum LSN is beyond me.

My solution? Just select from the tables directly. Yeah, I know, it's bad, unrecommended by Microsoft, reinventing the wheel. But it works and I don't get weird functions messing up my flow with obscure error messages. Just remember to take a look at the cdc.* functions and see how they are written.

So, to summarize: The error message is misleading and it's all they could do within the confines of the T-SQL function error system. Remember to use the schema in the string defining the table in the cdc functions (ex: dbo_MyTable). In case you really want to be flexible, interrogate the cdc tables directly.

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Timeout expired exception when rolling back SQL TransactionScope in .NET

I had this situation where I had to execute large SQL script files and the default sqlcmd tool was throwing exceptions rather than execute them. So I created my own tool to read the scripts and execute them transactionally. Everything went smoothly, except at the end. You see, I didn't use TransactionScope.Complete from the beginning in order to see how the program would cope with a massive rollback. Not well, apparently.

The exception was thrown at rollback: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. I had set the TransactionOptions.Timeout to TransactionManager.MaximumTimeout and the SqlCommand.CommandTimeout to 0 (meaning never end) and I still got the exception. Apparently, the problem was the SqlConnection.ConnectTimeout which is a readonly property with a default value of 15 seconds. The value can be changed via the connection string, by adding something like Connect Timeout=36000 (10 hours) and many articles on the Internet suggest doing that. However, that is just really ugly. A better solution is to set the value of the timeout programmatically and this is how to do it:

var timeout = TimeSpan.FromHours(10);
SqlConnectionStringBuilder csb = new SqlConnectionStringBuilder(connectionString);
csb.ConnectTimeout = (int)timeout.TotalSeconds;
connectionString = csb.ConnectionString;

As you can see, the nice SqlConnectionStringBuilder helps us validate, parse and change the values in the connection string. One can imagine other interesting uses, like adding MARS to the connection string automatically or restricting the use to a list of databases or disallowing weak passwords, etc.

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