On 05/07/2013 01:10 PM, Pádraig Brady wrote:
> On 05/06/2013 07:54 PM, Cojocaru Alexandru wrote:
>> On Mon, 29 Apr 2013 00:59:20 +0100
>> Pádraig Brady <p...@draigbrady.com> wrote:
>>
>>> So I reinstated the bit vector which was a little tricky
>>> to do while maintaining performance, but it works very well.
>> I think it works because we are avoiding a memory access
>> inside `next_item' this way.
>>
>> With this patch I try to keep the CPU benefits for `--output-d'
>> and when large ranges are specified, even without the bitarray.
>>
>> Because of the sentinel now the max line len supported will be
>> `(size_t)-1 - 1' and no more `(size_t)-1'. Is this an issue?
Not a practical one.
We could bump the types/limits in the range pairs
up to uintmax_t since we're now not allocating
lot of corresponding memory.
Note I added a specific check to make it
explicit that -b$SIZE_MAX is not supported if specified.
I'll do that in a subsequent patch, but it's
not a practical issue for now, as we still allocate mem
for the whole line.
The new patch performs well!
I'll apply the attached in a little while.
thanks!
Pádraig.
>From 1a6fbf21d1a70e85555a9b107f2f91188e2d3a4b Mon Sep 17 00:00:00 2001
From: Cojocaru Alexandru <xo...@gmx.com>
Date: Tue, 7 May 2013 13:47:15 +0100
Subject: [PATCH] cut: improve performance, especially with --output-delimiter
Use a sentinel value that's checked implicitly, rather than
a bit array, to determine if an item should be output.
Benchmark results for this change are:
$ yes abcdfeg | head -n1MB > big-file
$ for c in orig sentinel; do
src/cut-$c 2>/dev/null
echo -ne "\n== $c =="
time src/cut-$c -b1,3 big-file > /dev/null
done
== orig ==
real 0m0.049s
user 0m0.044s
sys 0m0.005s
== sentinel ==
real 0m0.035s
user 0m0.032s
sys 0m0.002s
## Again with --output-delimiter ##
$ for c in orig sentinel; do
src/cut-$c 2>/dev/null
echo -ne "\n== $c =="
time src/cut-$c -b1,3 --output-delimiter=: big-file > /dev/null
done
== orig ==
real 0m0.106s
user 0m0.103s
sys 0m0.002s
== sentinel ==
real 0m0.055s
user 0m0.052s
sys 0m0.003s
eol_range_start: Removed. 'n-' is no longer treated specially,
and instead SIZE_MAX is set for the 'hi' limit, and tested implicitly.
complement_rp: Used to complement 'rp' when '--complement' is specified.
ADD_RANGE_PAIR: Macro renamed to 'add_range_pair' function.
* tests/misc/cut-huge-range.sh: Adjust to the SENTINEL value.
---
src/cut.c | 234 +++++++++++++++---------------------------
tests/misc/cut-huge-range.sh | 15 ++-
2 files changed, 95 insertions(+), 154 deletions(-)
diff --git a/src/cut.c b/src/cut.c
index 9501b3a..19ef1d9 100644
--- a/src/cut.c
+++ b/src/cut.c
@@ -80,21 +80,15 @@ static size_t n_rp_allocated;
space if necessary. Update global variable N_RP. When allocating,
update global variable N_RP_ALLOCATED. */
-#define ADD_RANGE_PAIR(rp, low, high) \
- do \
- { \
- if (low == 0 || high == 0) \
- FATAL_ERROR (_("fields and positions are numbered from 1")); \
- if (n_rp >= n_rp_allocated) \
- { \
- (rp) = X2NREALLOC (rp, &n_rp_allocated); \
- } \
- rp[n_rp].lo = (low); \
- rp[n_rp].hi = (high); \
- ++n_rp; \
- } \
- while (0)
-
+static void
+add_range_pair (size_t lo, size_t hi)
+{
+ if (n_rp == n_rp_allocated)
+ rp = X2NREALLOC (rp, &n_rp_allocated);
+ rp[n_rp].lo = lo;
+ rp[n_rp].hi = hi;
+ ++n_rp;
+}
/* This buffer is used to support the semantics of the -s option
(or lack of same) when the specified field list includes (does
@@ -108,31 +102,6 @@ static char *field_1_buffer;
/* The number of bytes allocated for FIELD_1_BUFFER. */
static size_t field_1_bufsize;
-/* The largest field or byte index used as an endpoint of a closed
- or degenerate range specification; this doesn't include the starting
- index of right-open-ended ranges. For example, with either range spec
- '2-5,9-', '2-3,5,9-' this variable would be set to 5. */
-static size_t max_range_endpoint;
-
-/* If nonzero, this is the index of the first field in a range that goes
- to end of line. */
-static size_t eol_range_start;
-
-/* This is a bit vector.
- In byte mode, which bytes to output.
- In field mode, which DELIM-separated fields to output.
- Both bytes and fields are numbered starting with 1,
- so the zeroth bit of this array is unused.
- A field or byte K has been selected if
- (K <= MAX_RANGE_ENDPOINT && is_printable_field (K))
- || (EOL_RANGE_START > 0 && K >= EOL_RANGE_START). */
-static unsigned char *printable_field;
-
-/* The maximum size the printable_field array to allocate.
- For ranges requiring more than this, we revert to the slightly
- slower mechanism of inspecting the current range pair limits. */
-enum { PRINTABLE_ARRAY_MAX = 65536 };
-
enum operating_mode
{
undefined_mode,
@@ -151,7 +120,7 @@ static enum operating_mode operating_mode;
with field mode. */
static bool suppress_non_delimited;
-/* If nonzero, print all bytes, characters, or fields _except_
+/* If true, print all bytes, characters, or fields _except_
those that were specified. */
static bool complement;
@@ -253,56 +222,6 @@ With no FILE, or when FILE is -, read standard input.\n\
exit (status);
}
-static inline void
-mark_printable_field (size_t i)
-{
- size_t n = i / CHAR_BIT;
- printable_field[n] |= (1 << (i % CHAR_BIT));
-}
-
-static inline bool
-is_printable_field (size_t i)
-{
- size_t n = i / CHAR_BIT;
- return (printable_field[n] >> (i % CHAR_BIT)) & 1;
-}
-
-/* Return nonzero if the K'th field or byte is printable.
- Note this is a "hot" function. Please profile when changing. */
-
-static inline bool
-print_kth (size_t k)
-{
- bool k_selected = false;
-
- if (0 < eol_range_start && eol_range_start <= k)
- k_selected = true;
- else if (printable_field) /* faster path for smaller ranges. */
- {
- if (k <= max_range_endpoint && is_printable_field (k))
- k_selected = true;
- }
- else if (current_rp->lo <= k && k <= current_rp->hi)
- k_selected = true;
-
- return k_selected ^ complement;
-}
-
-/* Return nonzero if K'th byte is the beginning of a range. */
-
-static inline bool
-is_range_start_index (size_t k)
-{
- bool is_start = false;
-
- if (!complement)
- is_start = (k == eol_range_start || k == current_rp->lo);
- else
- is_start = (k == (current_rp - 1)->hi + 1);
-
- return is_start;
-}
-
/* Comparison function for qsort to order the list of
struct range_pairs. */
static int
@@ -313,22 +232,42 @@ compare_ranges (const void *a, const void *b)
return a_start < b_start ? -1 : a_start > b_start;
}
-/* Increment *ITEM_IDX (i.e. a field or byte index),
- and if required CURRENT_RP. */
+/* Reallocate Range Pair entries, with corresponding
+ entries outside the range of each specified entry. */
-static inline void
-next_item (size_t *item_idx)
+static void
+complement_rp (void)
{
- (*item_idx)++;
- /* avoid extra processing associated with current_rp unless needed. */
- if (!printable_field)
- if ((*item_idx > current_rp->hi) && (current_rp < rp + n_rp - 1))
- current_rp++;
+ if (complement)
+ {
+ struct range_pair *c = rp;
+ size_t n = n_rp;
+ size_t i;
+
+ rp = NULL;
+ n_rp = 0;
+ n_rp_allocated = 0;
+
+ if (c[0].lo > 1)
+ add_range_pair (1, c[0].lo - 1);
+
+ for (i = 1; i < n; ++i)
+ {
+ if (c[i-1].hi + 1 == c[i].lo)
+ continue;
+
+ add_range_pair (c[i-1].hi + 1, c[i].lo - 1);
+ }
+
+ if (c[n-1].hi < SIZE_MAX)
+ add_range_pair (c[n-1].hi + 1, SIZE_MAX);
+
+ free (c);
+ }
}
/* Given the list of field or byte range specifications FIELDSTR,
- allocate and initialize the RP array. If there is a right-open-ended
- range, set EOL_RANGE_START to its starting index. FIELDSTR should
+ allocate and initialize the RP array. FIELDSTR should
be composed of one or more numbers or ranges of numbers, separated
by blanks or commas. Incomplete ranges may be given: '-m' means '1-m';
'n-' means 'n' through end of line.
@@ -349,8 +288,7 @@ set_fields (const char *fieldstr)
size_t i;
bool in_digits = false;
- /* Collect and store in RP the range end points.
- It also sets EOL_RANGE_START if appropriate. */
+ /* Collect and store in RP the range end points. */
while (true)
{
@@ -385,10 +323,8 @@ set_fields (const char *fieldstr)
In any case, 'initial' contains the start of the range. */
if (!rhs_specified)
{
- /* 'n-'. From 'initial' to end of line. If we've already
- seen an M- range, ignore subsequent N- unless N < M. */
- if (eol_range_start == 0 || initial < eol_range_start)
- eol_range_start = initial;
+ /* 'n-'. From 'initial' to end of line. */
+ add_range_pair (initial, SIZE_MAX);
field_found = true;
}
else
@@ -397,7 +333,7 @@ set_fields (const char *fieldstr)
if (value < initial)
FATAL_ERROR (_("invalid decreasing range"));
- ADD_RANGE_PAIR (rp, initial, value);
+ add_range_pair (initial, value);
field_found = true;
}
value = 0;
@@ -405,7 +341,9 @@ set_fields (const char *fieldstr)
else
{
/* A simple field number, not a range. */
- ADD_RANGE_PAIR (rp, value, value);
+ if (value == 0)
+ FATAL_ERROR (_("fields and positions are numbered from 1"));
+ add_range_pair (value, value);
value = 0;
field_found = true;
}
@@ -432,7 +370,8 @@ set_fields (const char *fieldstr)
lhs_specified = 1;
/* Detect overflow. */
- if (!DECIMAL_DIGIT_ACCUMULATE (value, *fieldstr - '0', size_t))
+ if (!DECIMAL_DIGIT_ACCUMULATE (value, *fieldstr - '0', size_t)
+ || value == SIZE_MAX)
{
/* In case the user specified -c$(echo 2^64|bc),22,
complain only about the first number. */
@@ -455,40 +394,9 @@ set_fields (const char *fieldstr)
FATAL_ERROR (_("invalid byte, character or field list"));
}
- max_range_endpoint = 0;
- for (i = 0; i < n_rp; i++)
- {
- if (rp[i].hi > max_range_endpoint)
- max_range_endpoint = rp[i].hi;
- }
-
- /* For performance, allocate an array large enough so that it may be
- indexed by the field numbers corresponding to all finite ranges
- (i.e. '2-6' or '-4', but not '5-') in FIELDSTR.
- Note this enhancement is not possible with very large ranges,
- or when --output-delimiter is specified. */
-
- if (!output_delimiter_specified
- && max_range_endpoint
- && max_range_endpoint / CHAR_BIT < PRINTABLE_ARRAY_MAX)
- printable_field = xzalloc (max_range_endpoint / CHAR_BIT + 1);
-
qsort (rp, n_rp, sizeof (rp[0]), compare_ranges);
- /* Omit finite ranges subsumed by a to-EOL range. */
- if (eol_range_start && n_rp)
- {
- i = n_rp;
- while (i && eol_range_start <= rp[i - 1].hi)
- {
- eol_range_start = MIN (rp[i - 1].lo, eol_range_start);
- --n_rp;
- --i;
- }
- }
-
- /* Merge finite range pairs (e.g. `2-5,3-4' becomes `2-5').
- Also for small enough ranges, mark items as printable. */
+ /* Merge range pairs (e.g. `2-5,3-4' becomes `2-5'). */
for (i = 0; i < n_rp; ++i)
{
for (size_t j = i + 1; j < n_rp; ++j)
@@ -503,23 +411,47 @@ set_fields (const char *fieldstr)
else
break;
}
-
- if (printable_field)
- {
- for (size_t k = rp[i].lo; k <= rp[i].hi; k++)
- mark_printable_field (k);
- }
}
+ complement_rp ();
+
/* After merging, reallocate RP so we release memory to the system.
- Also add a sentinel at the end of RP, to avoid out of bounds access. */
+ Also add a sentinel at the end of RP, to avoid out of bounds access
+ and for perfomance reasons. */
++n_rp;
rp = xrealloc (rp, n_rp * sizeof (struct range_pair));
- rp[n_rp - 1].lo = rp[n_rp - 1].hi = 0;
+ rp[n_rp - 1].lo = rp[n_rp - 1].hi = SIZE_MAX;
return field_found;
}
+/* Increment *ITEM_IDX (i.e. a field or byte index),
+ and if required CURRENT_RP. */
+
+static inline void
+next_item (size_t *item_idx)
+{
+ (*item_idx)++;
+ if ((*item_idx) > current_rp->hi)
+ current_rp++;
+}
+
+/* Return nonzero if the K'th field or byte is printable. */
+
+static inline bool
+print_kth (size_t k)
+{
+ return current_rp->lo <= k;
+}
+
+/* Return nonzero if K'th byte is the beginning of a range. */
+
+static inline bool
+is_range_start_index (size_t k)
+{
+ return k == current_rp->lo;
+}
+
/* Read from stream STREAM, printing to standard output any selected bytes. */
static void
diff --git a/tests/misc/cut-huge-range.sh b/tests/misc/cut-huge-range.sh
index 9905cd7..579190f 100755
--- a/tests/misc/cut-huge-range.sh
+++ b/tests/misc/cut-huge-range.sh
@@ -21,13 +21,22 @@ print_ver_ cut
require_ulimit_v_
getlimits_
+# Ensure we can cut up to our sentinel value.
+# This is currently SIZE_MAX, but could be raised to UINTMAX_MAX
+# if we didn't allocate memory for each line as a unit.
+CUT_MAX=$(expr $SIZE_MAX - 1)
+
# From coreutils-8.10 through 8.20, this would make cut try to allocate
# a 256MiB bit vector. With a 20MB limit on VM, the following would fail.
-(ulimit -v 20000; : | cut -b$INT_MAX- > err 2>&1) || fail=1
+(ulimit -v 20000; : | cut -b$CUT_MAX- > err 2>&1) || fail=1
# Up to and including coreutils-8.21, cut would allocate possibly needed
-# memory upfront. Subsequently memory is allocated as required.
-(ulimit -v 20000; : | cut -b1-$INT_MAX >> err 2>&1) || fail=1
+# memory upfront. Subsequently extra memory is no longer needed.
+(ulimit -v 20000; : | cut -b1-$CUT_MAX >> err 2>&1) || fail=1
+
+# Explicitly disallow values above CUT_MAX
+(ulimit -v 20000; : | cut -b$SIZE_MAX 2>/dev/null) && fail=1
+(ulimit -v 20000; : | cut -b$SIZE_OFLOW 2>/dev/null) && fail=1
# Ensure ranges are merged correctly when large range logic is in effect
echo 1 > exp
--
1.7.7.6
