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Refactor unit conversions code in guc.c.
Replace the if-switch-case constructs with two conversion tables, containing all the supported conversions between human-readable unit strings and the base units used in GUC variables. This makes the code easier to read, and makes adding new units simpler.
This commit is contained in:
Heikki Linnakangas
parent
bc208a5a2f
commit
1b63026473
@ -97,20 +97,6 @@
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#define CONFIG_EXEC_PARAMS_NEW "global/config_exec_params.new"
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#endif
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#define KB_PER_MB (1024)
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#define KB_PER_GB (1024*1024)
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#define KB_PER_TB (1024*1024*1024)
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#define MS_PER_S 1000
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#define S_PER_MIN 60
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#define MS_PER_MIN (1000 * 60)
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#define MIN_PER_H 60
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#define S_PER_H (60 * 60)
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#define MS_PER_H (1000 * 60 * 60)
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#define MIN_PER_D (60 * 24)
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#define S_PER_D (60 * 60 * 24)
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#define MS_PER_D (1000 * 60 * 60 * 24)
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/*
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* Precision with which REAL type guc values are to be printed for GUC
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* serialization.
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@ -666,6 +652,88 @@ const char *const config_type_names[] =
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/* PGC_ENUM */ "enum"
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};
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/*
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* Unit conversion tables.
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*
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* There are two tables, one for memory units, and another for time units.
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* For each supported conversion from one unit to another, we have an entry
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* in the table.
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*
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* To keep things simple, and to avoid intermediate-value overflows,
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* conversions are never chained. There needs to be a direct conversion
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* between all units (of the same type).
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*
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* The conversions from each base unit must be kept in order from greatest
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* to smallest unit; convert_from_base_unit() relies on that. (The order of
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* the base units does not matter.)
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*/
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#define MAX_UNIT_LEN 3 /* length of longest recognized unit string */
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typedef struct
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{
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char unit[MAX_UNIT_LEN + 1]; /* unit, as a string, like "kB" or "min" */
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int base_unit; /* GUC_UNIT_XXX */
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int multiplier; /* If positive, multiply the value with this for
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* unit -> base_unit conversion. If negative,
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* divide (with the absolute value) */
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} unit_conversion;
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/* Ensure that the constants in the tables don't overflow or underflow */
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#if BLCKSZ < 1024 || BLCKSZ > (1024*1024)
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#error BLCKSZ must be between 1KB and 1MB
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#endif
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#if XLOG_BLCKSZ < 1024 || XLOG_BLCKSZ > (1024*1024)
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#error XLOG_BLCKSZ must be between 1KB and 1MB
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#endif
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static const char *memory_units_hint =
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gettext_noop("Valid units for this parameter are \"kB\", \"MB\", \"GB\", and \"TB\".");
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static const unit_conversion memory_unit_conversion_table[] =
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{
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{ "TB", GUC_UNIT_KB, 1024*1024*1024 },
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{ "GB", GUC_UNIT_KB, 1024*1024 },
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{ "MB", GUC_UNIT_KB, 1024 },
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{ "kB", GUC_UNIT_KB, 1 },
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{ "TB", GUC_UNIT_BLOCKS, (1024*1024*1024) / (BLCKSZ / 1024) },
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{ "GB", GUC_UNIT_BLOCKS, (1024*1024) / (BLCKSZ / 1024) },
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{ "MB", GUC_UNIT_BLOCKS, 1024 / (BLCKSZ / 1024) },
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{ "kB", GUC_UNIT_BLOCKS, -(BLCKSZ / 1024) },
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{ "TB", GUC_UNIT_XBLOCKS, (1024*1024*1024) / (XLOG_BLCKSZ / 1024) },
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{ "GB", GUC_UNIT_XBLOCKS, (1024*1024) / (XLOG_BLCKSZ / 1024) },
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{ "MB", GUC_UNIT_XBLOCKS, 1024 / (XLOG_BLCKSZ / 1024) },
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{ "kB", GUC_UNIT_XBLOCKS, -(XLOG_BLCKSZ / 1024) },
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{ "" } /* end of table marker */
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};
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static const char *time_units_hint =
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gettext_noop("Valid units for this parameter are \"ms\", \"s\", \"min\", \"h\", and \"d\".");
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static const unit_conversion time_unit_conversion_table[] =
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{
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{ "d", GUC_UNIT_MS, 1000 * 60 * 60 * 24 },
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{ "h", GUC_UNIT_MS, 1000 * 60 * 60 },
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{ "min", GUC_UNIT_MS, 1000 * 60},
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{ "s", GUC_UNIT_MS, 1000 },
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{ "ms", GUC_UNIT_MS, 1 },
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{ "d", GUC_UNIT_S, 60 * 60 * 24 },
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{ "h", GUC_UNIT_S, 60 * 60 },
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{ "min", GUC_UNIT_S, 60 },
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{ "s", GUC_UNIT_S, 1 },
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{ "ms", GUC_UNIT_S, -1000 },
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{ "d", GUC_UNIT_MIN, 60 * 24 },
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{ "h", GUC_UNIT_MIN, 60 },
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{ "min", GUC_UNIT_MIN, 1 },
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{ "s", GUC_UNIT_MIN, -60 },
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{ "ms", GUC_UNIT_MIN, -1000 * 60 },
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{ "" } /* end of table marker */
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};
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/*
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* Contents of GUC tables
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@ -5029,6 +5097,88 @@ ReportGUCOption(struct config_generic * record)
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}
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}
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/*
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* Convert a value from one of the human-friendly units ("kB", "min" etc.)
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* to the given base unit. 'value' and 'unit' are the input value and unit
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* to convert from. The converted value is stored in *base_value.
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*
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* Returns true on success, false if the input unit is not recognized.
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*/
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static bool
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convert_to_base_unit(int64 value, const char *unit,
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int base_unit, int64 *base_value)
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{
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const unit_conversion *table;
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int i;
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if (base_unit & GUC_UNIT_MEMORY)
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table = memory_unit_conversion_table;
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else
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table = time_unit_conversion_table;
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for (i = 0; *table[i].unit; i++)
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{
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if (base_unit == table[i].base_unit &&
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strcmp(unit, table[i].unit) == 0)
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{
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if (table[i].multiplier < 0)
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*base_value = value / (-table[i].multiplier);
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else
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*base_value = value * table[i].multiplier;
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return true;
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}
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}
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return false;
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}
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/*
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* Convert a value in some base unit to a human-friendly unit. The output
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* unit is chosen so that it's the greatest unit that can represent the value
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* without loss. For example, if the base unit is GUC_UNIT_KB, 1024 is
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* converted to 1 MB, but 1025 is represented as 1025 kB.
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*/
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static void
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convert_from_base_unit(int64 base_value, int base_unit,
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int64 *value, const char **unit)
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{
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const unit_conversion *table;
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int i;
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*unit = NULL;
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if (base_unit & GUC_UNIT_MEMORY)
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table = memory_unit_conversion_table;
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else
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table = time_unit_conversion_table;
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for (i = 0; *table[i].unit; i++)
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{
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if (base_unit == table[i].base_unit)
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{
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/*
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* Accept the first conversion that divides the value evenly.
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* We assume that the conversions for each base unit are ordered
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* from greatest unit to the smallest!
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*/
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if (table[i].multiplier < 0)
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{
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*value = base_value * (-table[i].multiplier);
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*unit = table[i].unit;
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break;
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}
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else if (base_value % table[i].multiplier == 0)
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{
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*value = base_value / table[i].multiplier;
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*unit = table[i].unit;
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break;
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}
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}
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}
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Assert(*unit != NULL);
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}
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/*
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* Try to parse value as an integer. The accepted formats are the
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* usual decimal, octal, or hexadecimal formats, optionally followed by
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@ -5072,170 +5222,37 @@ parse_int(const char *value, int *result, int flags, const char **hintmsg)
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/* Handle possible unit */
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if (*endptr != '\0')
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{
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/*
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* Note: the multiple-switch coding technique here is a bit tedious,
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* but seems necessary to avoid intermediate-value overflows.
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*/
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if (flags & GUC_UNIT_MEMORY)
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{
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/* Set hint for use if no match or trailing garbage */
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if (hintmsg)
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*hintmsg = gettext_noop("Valid units for this parameter are \"kB\", \"MB\", \"GB\", and \"TB\".");
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char unit[MAX_UNIT_LEN + 1];
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int unitlen;
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bool converted = false;
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#if BLCKSZ < 1024 || BLCKSZ > (1024*1024)
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#error BLCKSZ must be between 1KB and 1MB
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#endif
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#if XLOG_BLCKSZ < 1024 || XLOG_BLCKSZ > (1024*1024)
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#error XLOG_BLCKSZ must be between 1KB and 1MB
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#endif
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if (strncmp(endptr, "kB", 2) == 0)
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{
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endptr += 2;
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switch (flags & GUC_UNIT_MEMORY)
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{
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case GUC_UNIT_BLOCKS:
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val /= (BLCKSZ / 1024);
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break;
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case GUC_UNIT_XBLOCKS:
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val /= (XLOG_BLCKSZ / 1024);
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break;
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}
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}
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else if (strncmp(endptr, "MB", 2) == 0)
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{
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endptr += 2;
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switch (flags & GUC_UNIT_MEMORY)
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{
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case GUC_UNIT_KB:
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val *= KB_PER_MB;
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break;
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case GUC_UNIT_BLOCKS:
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val *= KB_PER_MB / (BLCKSZ / 1024);
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break;
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case GUC_UNIT_XBLOCKS:
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val *= KB_PER_MB / (XLOG_BLCKSZ / 1024);
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break;
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}
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}
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else if (strncmp(endptr, "GB", 2) == 0)
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{
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endptr += 2;
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switch (flags & GUC_UNIT_MEMORY)
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{
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case GUC_UNIT_KB:
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val *= KB_PER_GB;
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break;
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case GUC_UNIT_BLOCKS:
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val *= KB_PER_GB / (BLCKSZ / 1024);
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break;
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case GUC_UNIT_XBLOCKS:
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val *= KB_PER_GB / (XLOG_BLCKSZ / 1024);
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break;
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}
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}
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else if (strncmp(endptr, "TB", 2) == 0)
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{
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endptr += 2;
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switch (flags & GUC_UNIT_MEMORY)
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{
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case GUC_UNIT_KB:
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val *= KB_PER_TB;
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break;
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case GUC_UNIT_BLOCKS:
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val *= KB_PER_TB / (BLCKSZ / 1024);
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break;
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case GUC_UNIT_XBLOCKS:
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val *= KB_PER_TB / (XLOG_BLCKSZ / 1024);
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break;
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}
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}
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}
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else if (flags & GUC_UNIT_TIME)
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{
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/* Set hint for use if no match or trailing garbage */
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if (hintmsg)
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*hintmsg = gettext_noop("Valid units for this parameter are \"ms\", \"s\", \"min\", \"h\", and \"d\".");
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if (strncmp(endptr, "ms", 2) == 0)
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{
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endptr += 2;
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switch (flags & GUC_UNIT_TIME)
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{
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case GUC_UNIT_S:
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val /= MS_PER_S;
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break;
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case GUC_UNIT_MIN:
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val /= MS_PER_MIN;
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break;
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}
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}
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else if (strncmp(endptr, "s", 1) == 0)
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{
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endptr += 1;
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switch (flags & GUC_UNIT_TIME)
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{
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case GUC_UNIT_MS:
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val *= MS_PER_S;
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break;
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case GUC_UNIT_MIN:
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val /= S_PER_MIN;
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break;
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}
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}
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else if (strncmp(endptr, "min", 3) == 0)
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{
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endptr += 3;
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switch (flags & GUC_UNIT_TIME)
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{
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case GUC_UNIT_MS:
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val *= MS_PER_MIN;
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break;
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case GUC_UNIT_S:
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val *= S_PER_MIN;
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break;
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}
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}
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else if (strncmp(endptr, "h", 1) == 0)
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{
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endptr += 1;
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switch (flags & GUC_UNIT_TIME)
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{
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case GUC_UNIT_MS:
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val *= MS_PER_H;
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break;
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case GUC_UNIT_S:
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val *= S_PER_H;
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break;
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case GUC_UNIT_MIN:
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val *= MIN_PER_H;
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break;
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}
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}
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else if (strncmp(endptr, "d", 1) == 0)
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{
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endptr += 1;
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switch (flags & GUC_UNIT_TIME)
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{
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case GUC_UNIT_MS:
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val *= MS_PER_D;
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break;
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case GUC_UNIT_S:
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val *= S_PER_D;
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break;
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case GUC_UNIT_MIN:
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val *= MIN_PER_D;
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break;
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}
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}
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}
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if ((flags & GUC_UNIT) == 0)
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return false; /* this setting does not accept a unit */
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unitlen = 0;
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while (*endptr != '\0' && !isspace((unsigned char) *endptr) &&
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unitlen < MAX_UNIT_LEN)
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unit[unitlen++] = *(endptr++);
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unit[unitlen] = '\0';
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/* allow whitespace after unit */
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while (isspace((unsigned char) *endptr))
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endptr++;
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if (*endptr != '\0')
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return false; /* appropriate hint, if any, already set */
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if (*endptr == '\0')
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converted = convert_to_base_unit(val, unit, (flags & GUC_UNIT),
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&val);
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if (!converted)
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{
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/* invalid unit, or garbage after the unit; set hint and fail. */
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if (hintmsg)
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{
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if (flags & GUC_UNIT_MEMORY)
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*hintmsg = memory_units_hint;
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else
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*hintmsg = time_units_hint;
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}
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return false;
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}
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/* Check for overflow due to units conversion */
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if (val != (int64) ((int32) val))
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@ -8108,76 +8125,10 @@ _ShowOption(struct config_generic * record, bool use_units)
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int64 result = *conf->variable;
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const char *unit;
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if (use_units && result > 0 &&
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(record->flags & GUC_UNIT_MEMORY))
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if (use_units && result > 0 && (record->flags & GUC_UNIT))
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{
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switch (record->flags & GUC_UNIT_MEMORY)
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{
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case GUC_UNIT_BLOCKS:
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result *= BLCKSZ / 1024;
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break;
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case GUC_UNIT_XBLOCKS:
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result *= XLOG_BLCKSZ / 1024;
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break;
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}
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if (result % KB_PER_TB == 0)
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{
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result /= KB_PER_TB;
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unit = "TB";
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}
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else if (result % KB_PER_GB == 0)
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{
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result /= KB_PER_GB;
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unit = "GB";
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}
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else if (result % KB_PER_MB == 0)
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{
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result /= KB_PER_MB;
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unit = "MB";
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}
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else
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{
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unit = "kB";
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}
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}
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else if (use_units && result > 0 &&
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(record->flags & GUC_UNIT_TIME))
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{
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switch (record->flags & GUC_UNIT_TIME)
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{
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case GUC_UNIT_S:
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result *= MS_PER_S;
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break;
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case GUC_UNIT_MIN:
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result *= MS_PER_MIN;
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break;
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}
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if (result % MS_PER_D == 0)
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{
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result /= MS_PER_D;
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unit = "d";
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}
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else if (result % MS_PER_H == 0)
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{
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result /= MS_PER_H;
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unit = "h";
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}
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else if (result % MS_PER_MIN == 0)
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{
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result /= MS_PER_MIN;
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unit = "min";
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}
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else if (result % MS_PER_S == 0)
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{
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result /= MS_PER_S;
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unit = "s";
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}
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else
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{
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unit = "ms";
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}
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convert_from_base_unit(result, record->flags & GUC_UNIT,
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&result, &unit);
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}
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else
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unit = "";
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@ -212,6 +212,8 @@ typedef enum
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#define GUC_UNIT_MIN 0x4000 /* value is in minutes */
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#define GUC_UNIT_TIME 0x7000 /* mask for MS, S, MIN */
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#define GUC_UNIT (GUC_UNIT_MEMORY | GUC_UNIT_TIME)
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#define GUC_NOT_WHILE_SEC_REST 0x8000 /* can't set if security restricted */
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#define GUC_DISALLOW_IN_AUTO_FILE 0x00010000 /* can't set in
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* PG_AUTOCONF_FILENAME */
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