Hello,
Marc Alff a écrit, Le 01.04.2010 10:08:
> #At file:///Users/malff/BZR_TREE/mysql-next-mr-bugfixing-52502/ based on
> revid:alik@stripped
>
> 3144 Marc Alff 2010-04-01
> Bug#52502 Performance schema does not start with large mutex_instance buffers
> === modified file 'storage/perfschema/pfs_instr.cc'
> --- a/storage/perfschema/pfs_instr.cc 2010-03-22 12:48:18 +0000
> +++ b/storage/perfschema/pfs_instr.cc 2010-04-01 08:08:12 +0000
> @@ -445,6 +445,77 @@ void cleanup_file_hash(void)
> }
> }
>
> +void PFS_scan::init(uint random, uint max_size)
> +{
I'd do a single unconditional m_pass=0 here: m_pass is a counter of the
number of passes already done, and when the object is not yet used this
counter should always be 0 (kind of, by definition), so it makes sense
to set it here (and it saves a bit of code too, by eliminating m_pass=0
in branches below).
> + if (max_size == 0)
> + {
> + /* Degenerated case, no buffer */
> + m_pass= 0;
> + m_pass_max= 0;
> + return;
> + }
> === modified file 'storage/perfschema/pfs_instr.h'
> --- a/storage/perfschema/pfs_instr.h 2010-01-12 01:47:27 +0000
> +++ b/storage/perfschema/pfs_instr.h 2010-04-01 08:08:12 +0000
> @@ -136,6 +136,48 @@ struct PFS_table : public PFS_instr
> */
> #define LOCKER_STACK_SIZE 3
>
> +/**
> + @def PFS_MAX_ALLOC_RETRY
> + Maximum number of times the code attempts to allocate an item
> + from internal buffers, before giving up.
> +*/
> +#define PFS_MAX_ALLOC_RETRY 1000
> +
> +#define PFS_MAX_SCAN_PASS 2
> +
> +/**
> + Helper to scan circular buffers.
> + Given a buffer of size [0, max_size - 1],
> + and a random starting point in the buffer,
> + this helper returns up to two [first, last -1] intervals that:
> + - fit into the [0, max_size - 1] range,
> + - have a maximum combined length of at most PFS_MAX_ALLOC_RETRY.
> +*/
> +struct PFS_scan
> +{
> +public:
> + void init(uint random, uint max_size);
At your option, PFS_scan could also be a class and init() would be its
constructor.
> + bool has_pass() const
> + { return (m_pass < m_pass_max); }
> +
> + void next_pass()
> + { m_pass++; }
> +
> + uint first()
can be made "const"
> + { return m_first[m_pass]; }
> +
> + uint last()
same
> + { return m_last[m_pass]; }
> +
> +private:
> + uint m_pass;
> + uint m_pass_max;
> + uint m_first[PFS_MAX_SCAN_PASS];
> + uint m_last[PFS_MAX_SCAN_PASS];
> +};
> +
A quite clean patch, thanks. Ok to push.
