Move repository to Gitea

On systems that do not support fallocate() (NFS, BeeGFS),
posix_fallocate() emulates the allocation by writing zeros
which is extremely inefficient.

In these cases we would rather skip-preallocation and
simply use ftruncate() to set the file size without allocating.

.gitignore

@@ -1,4 +1,4 @@
 *.o
 *~
-sortbin
-recgen
+/build
+/tests/testdata

COPYING

@@ -0,0 +1,674 @@
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+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<http://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<http://www.gnu.org/philosophy/why-not-lgpl.html>.

Makefile

@@ -4,25 +4,38 @@
 
 CXX = g++
 CXXFLAGS = -Wall -O2 -pthread
-  # -fsanitize=address -fsanitize=undefined
+CXXFLAGS_DEBUG = -g -fsanitize=address -fsanitize=undefined -fsanitize=leak
 
 SRCDIR = src
 BUILDDIR = build
 
 TOOLS = sortbin recgen
 BINFILES = $(patsubst %,$(BUILDDIR)/%,$(TOOLS))
+BINFILES_DEBUG = $(patsubst %,$(BUILDDIR)/%_dbg,$(TOOLS))
 
 .PHONY: all
 all: $(BINFILES)
 
+.PHONY: test
+test: $(BINFILES_DEBUG)
+	cd tests ; ./run_tests.sh
+
 $(BUILDDIR)/sortbin: $(SRCDIR)/sortbin.cpp
-$(BUILDDIR)/recgen: $(SRCDIR)/recgen.cpp
+$(BUILDDIR)/recgen: $(SRCDIR)/recgen.cpp $(SRCDIR)/xoroshiro128plus.h
+
+$(BUILDDIR)/sortbin_dbg: $(SRCDIR)/sortbin.cpp
+$(BUILDDIR)/recgen_dbg: $(SRCDIR)/recgen.cpp $(SRCDIR)/xoroshiro128plus.h
 
 $(BUILDDIR)/%: $(SRCDIR)/%.cpp
 	@mkdir -p $(BUILDDIR)
 	$(CXX) $(CPPFLAGS) $(CXXFLAGS) $(LDFLAGS) $< $(LDLIBS) -o $@
 
+$(BUILDDIR)/%_dbg: $(SRCDIR)/%.cpp
+	@mkdir -p $(BUILDDIR)
+	$(CXX) $(CPPFLAGS) $(CXXFLAGS) $(CXXFLAGS_DEBUG) $(LDFLAGS) $< $(LDLIBS) -o $@
+
 .PHONY: clean
 clean:
-	$(RM) $(BINFILES)
+	$(RM) $(BINFILES) $(BINFILES_DEBUG)
+	$(RM) -r tests/testdata
 

README.md

@@ -10,7 +10,7 @@ These files contain flat, raw arrays of binary data records.
 
 Records are interpreted as fixed-length strings of 8-bit unsigned integers.
 These records are sorted in lexicographic order.
-This means that records are sorted by their first byte, then records with equal first bytes are sorted by their second bytes, and so on.
+This means that records are sorted by their first byte, records with equal first bytes are sorted by their second bytes, and so on.
 
 SortBin can sort very large data files which do not fit in memory.
 In such cases, a temporary file is used to store intermediate results.
@@ -20,6 +20,7 @@ It then iteratively merges these blocks into larger sorted blocks until the comp
 This program is designed to work with relatively short data records, up to about 20 bytes.
 Sorting larger records should work, but may be inefficient.
 
+
 ## Usage
 
 SortBin has only been tested on Linux.
@@ -27,16 +28,135 @@ SortBin has only been tested on Linux.
 To use SortBin, you must compile the source code.
 Clone the repository, then build as follows:
 ```
-git clone https://github.com/jorisvr/sortbin.git
+git clone https://git.jorisvr.nl/joris/sortbin.git
 cd sortbin
 make
 ```
 
 You can now sort data like this:
 ```
-build/sortbin --size=10 --memory=2G input.dat output.dat
+build/sortbin --size=10 input.dat output.dat
+```
+where _size_ specifies the record size in bytes.
+
+The tool has a bunch of options that can be used to tune its performance:
+```
+Usage: sortbin [options] inputfile outputfile
+
+Options:
+
+  -s, --size=N
+        Specify record size of N bytes (required)
+
+  -u, --unique
+        Eliminate duplicates after sorting
+
+  --memory=<n>M, --memory=<n>G
+        Specify the amount of RAM that may be used.
+        Use suffix 'M' for MiByte, or 'G' for GiByte. (default: 1024 MiB)
+
+  --branch=N
+        Merge at most N subarrays in one step. (default: 16)
+
+  --parallel=N
+        Use N threads for parallel sorting. (default: 1)
+
+  --iothread / --no-iothread
+        Enable or disable use of background threads for I/O.
+        (default: enable)
+
+  -T, --temporary-directory=DIR
+        Write temporary file to the specified directory. (default: $TMPDIR)
+
+  -v, --verbose
+        Write progress messages to STDERR.
 ```
 
-* _size_ specifies the record size in bytes
-* _memory_ specifies the amount of RAM that SortBin may use
+For input files that fit in memory, the best way to get good performance is making sure that the tool can allocate enough memory to contain the file, and optionally increasing the number of threads.
+
+For input files that do not fit in memory, the best way to get good performance is minimizing the number of required merge passes. This can be done by increasing the _branch factor_, and to a lesser degree by increasing the amount of memory.
+
+
+## Status of this software
+
+SortBin is just a hobby project, not production-quality software.
+
+My limited testing suggests that the tool works correctly and is reasonably efficient.
+Testing was done on Linux, but the tool should probably also work on other POSIX systems.
+
+
+## How it works
+
+If the input file fits in memory, SortBin simply runs an in-place quicksort on the whole file.
+Optionally, multiple threads may be used to run the quicksort algorithm on parallel CPU cores.
+
+If the file does not fit in memory, SortBin uses a sort-then-merge strategy:
+ - Create a temporary file with the same size as the input.
+ - Chop the input into blocks that fit in memory. Read each block, sort it with quicksort, then write to the temporary file.
+ - Read multiple sorted blocks from the temporary file and merge them into a bigger sorted block. By default, SortBin does a 16-way merge but this is configurable.
+ - Continue merging sorted blocks into bigger sorted blocks until only 1 block is left. That block contains the final sorted output.
+
+Optionally, multiple threads may be used to speed up the sorting phase by running the quicksort algorithm on parallel CPU cores.
+
+By default, the sort-then-merge strategy delegates disk I/O to a separate thread so that I/O and CPU processing can occur simultaneously.
+
+
+## Performance
+
+I compared the performance of SortBin to that of GNU sort.
+This is in many ways an unfair comparison.
+The GNU sort utility was designed to sort lines of text, is highly customizable and is expected to show reasonable performance on a wide range of computer systems.
+In contrast, SortBin can only sort fixed-length records, is not customizable, and was optimized for sorting big files of small records on a modern PC.
+
+I tested the performance by sorting a 100 GB file using only 1 GB memory.
+For GNU sort, I allowed 2 GB memory because it seems to use a significant amount of memory to keep track of lines of text.
+For SortBin, I set the number of parallel sort threads to 4.
+
+I tested on Linux, x86\_64 CPU with 6 cores, 3600 MHz, 5980 rpm SATA harddisk.
+My performance figures should be taken with a big pinch of salt.
+I have not checked how accurate these results reproduce on the same system or on other systems.
+And I did not try very hard to keep background processes from potentially influencing the results.
+
+| Input size | Records | Record size | Program  | Duration  | CPU time  |
+| ---------- | ------- | ----------- | -------- | --------- | --------  |
+| 100 GB     | 1e10    | 10 bytes    | GNU sort | 6.5 hours | 9.9 hours |
+| 100 GB     | 1e10    | 10 bytes    | SortBin  | 1.2 hours | 1.0 hours |
+| 100 GB     | 2e9     | 50 bytes    | GNU sort | 1.8 hours | 1.9 hours |
+| 100 GB     | 2e9     | 50 bytes    | SortBin  | 1.2 hours | 0.4 hours |
+
+For what it's worth, SortBin appears to be much faster than GNU sort when sorting small binary records.
+This performance advantage decreases as records get bigger.
+
+
+## Credits
+
+While writing SortBin, I used ideas from several other software packages:
+ - GNU sort, the standard `sort` utility of the GNU project, <br>
+   part of coreutils: https://www.gnu.org/software/coreutils/
+ - The implementation of `qsort()` in the GNU C Library. <br>
+   https://www.gnu.org/software/libc/
+ - The implementation of `std::sort()` in the GNU C++ Library. <br>
+   https://gcc.gnu.org/onlinedocs/libstdc++/
+
+To test SortBin, I wrote a tool to generate random binary records.
+It uses the pseudo-random number generator Xoroshiro128+ from
+https://prng.di.unimi.it/xoroshiro128plus.c
+
+
+## License
+
+Copyright (C) 2022 Joris van Rantwijk
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see http://www.gnu.org/licenses/ .
 

src/recgen.cpp

@@ -1,7 +1,20 @@
 /*
  * Tool to generate random binary data records.
  *
- * Written by Joris van Rantwijk in 2022.
+ * Copyright (c) 2022 Joris van Rantwijk
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #define _FILE_OFFSET_BITS 64
@@ -19,6 +32,7 @@
 
 #include <vector>
 
+#include "xoroshiro128plus.h"
 
 #define MAX_RECORD_SIZE             65536
 #define REPORT_INTERVAL             1000000
@@ -27,79 +41,6 @@
 namespace {  // anonymous namespace
 
 
-/**
- * Pseudo random number generator "xoroshiro128+"
- *
- * This code is based on the reference implementation,
- * modified by Joris van Rantwijk to fit in a C++ class.
- *
- * Source: http://prng.di.unimi.it/
- *
- * The following commpents apply to the reference implementation:
- *
- * Written in 2016-2018 by David Blackman and Sebastiano Vigna (vigna@acm.org)
- *
- * To the extent possible under law, the author has dedicated all copyright
- * and related and neighboring rights to this software to the public domain
- * worldwide. This software is distributed without any warranty.
- *
- * See <http://creativecommons.org/publicdomain/zero/1.0/>.
- *
- * This is xoroshiro128+ 1.0, our best and fastest small-state generator
- * for floating-point numbers. We suggest to use its upper bits for
- * floating-point generation, as it is slightly faster than
- * xoroshiro128++/xoroshiro128**. It passes all tests we are aware of
- * except for the four lower bits, which might fail linearity tests (and
- * just those), so if low linear complexity is not considered an issue (as
- * it is usually the case) it can be used to generate 64-bit outputs, too;
- * moreover, this generator has a very mild Hamming-weight dependency
- * making our test (http://prng.di.unimi.it/hwd.php) fail after 5 TB of
- * output; we believe this slight bias cannot affect any application. If
- * you are concerned, use xoroshiro128++, xoroshiro128** or xoshiro256+.
- *
- * We suggest to use a sign test to extract a random Boolean value, and
- * right shifts to extract subsets of bits.
- *
- * The state must be seeded so that it is not everywhere zero. If you have
- * a 64-bit seed, we suggest to seed a splitmix64 generator and use its
- * output to fill s.
- *
- * NOTE: the parameters (a=24, b=16, b=37) of this version give slightly
- * better results in our test than the 2016 version (a=55, b=14, c=36).
- */
-class Xoroshiro128plus
-{
-public:
-    Xoroshiro128plus(uint64_t s0, uint64_t s1)
-    {
-        m_state[0] = s0;
-        m_state[1] = s1;
-    }
-
-    inline uint64_t next()
-    {
-        const uint64_t s0 = m_state[0];
-        uint64_t s1 = m_state[1];
-        const uint64_t result = s0 + s1;
-
-        s1 ^= s0;
-        m_state[0] = rotl(s0, 24) ^ s1 ^ (s1 << 16);
-        m_state[1] = rotl(s1, 37);
-
-        return result;
-    }
-
-private:
-    static inline uint64_t rotl(uint64_t x, int k)
-    {
-        return (x << k) | (x >> (64 - k));
-    }
-
-    uint64_t m_state[2];
-};
-
-
-
 class RecordGenerator
 {
 public:
@@ -149,8 +90,8 @@ public:
             //   N = log(1 - U/V) / log(1 - 1/V)
             //
             if (info_per_record >= 128) {
-                // The number of records is so big that we can just pretend
-                // that every key will produce a different record.
+                // There are so many different records that we can just
+                // pretend that every key will produce a different record.
             } else {
                 double v = exp(info_per_record * M_LN2);
 
@@ -182,7 +123,7 @@ public:
 
             // Determine the number of random bits for which the
             // expected number of unique keys matches our target.
-            // First scan in steps of 1 bit.
+            // Coarse scan in steps of 1 bit.
             unsigned int need_bits = 2;
             while (need_bits < 127) {
                 double expected_unique =
@@ -223,19 +164,22 @@ public:
     void generate_record(unsigned char * record, Xoroshiro128plus& rng)
     {
         if (m_make_duplicates) {
-            // We have a budget of fewer than 128 random bits per record.
-            // Create a random seed value of that many bits.
-            // Then use it to initialize a secondary random number generator.
-            // Then use that generator to generate the actual record.
+            // We want a specific fraction of duplicate records.
+            // Instead of drawing a random record from a uniform distribution
+            // of all possible records, we draw a random key from a limited
+            // set, then map that key to a record.
 
-            // During the first call, generate a salt for the secondary
-            // random number generator. Without this salt, every run
-            // would sample from the same subset of records.
+            // During the first call, generate a salt for the mapping from
+            // key to record. Without this salt, repeated runs would sample
+            // from the same subset of records even when using different
+            // random seeds.
             if (!m_salt_initialized) {
                 m_salt = rng.next();
                 m_salt_initialized = true;
             }
 
+            // Draw a random key with the chosen number of bits.
+            // Apply a threshold to draw a "fractional" number of bits.
             uint64_t s0 = 0, s1 = 0;
             unsigned int need_bits = m_bits_per_record;
             if (need_bits > 64) {
@@ -246,16 +190,20 @@ public:
                 s1 = rng.next();
             } while (s1 > m_highbit_threshold);
             s1 >>= (64 - need_bits);
+
+            // Mix salt into the key.
             s0 ^= m_salt;
 
-            // Create secondary random number generator.
+            // Use the key to initialize a secondary random number generator.
             Xoroshiro128plus rng2(s0, s1);
             rng2.next();
             rng2.next();
 
-            // Use it to generate a record.
+            // Use secondary generator to map the key to a record.
             generate_uniform_record(record, rng2);
+
         } else {
+
             // Uniform distribution of records.
             generate_uniform_record(record, rng);
         }
@@ -350,7 +298,7 @@ int recgen(
     }
 
     FILE *outf = fdopen(fd, "w");
-    if (outf == NULL) {
+    if (outf == nullptr) {
         fprintf(stderr, "ERROR: fdopen() failed (%s)\n", strerror(errno));
         close(fd);
         return -1;
@@ -402,11 +350,22 @@ void usage()
 }
 
 
+void usage_short()
+{
+    fprintf(stderr, "Run 'recgen --help' for usage instructions.\n");
+}
+
+
 } // anonymous namespace
 
 
 int main(int argc, char **argv)
 {
+    const struct option longopts[] = {
+        { "help", 0, nullptr, 'h' },
+        { nullptr, 0, nullptr, 0 }
+    };
+
     double duplicate_fraction = 0.0;
     unsigned long long num_records = 0;
     unsigned long record_size = 0;
@@ -414,7 +373,8 @@ int main(int argc, char **argv)
     unsigned long long seed = 1;
     int opt;
 
-    while ((opt = getopt(argc, argv, "ad:n:s:S:")) != -1) {
+    while ((opt = getopt_long(argc, argv, "ad:n:s:S:h", longopts, nullptr))
+           != -1) {
         char *endptr;
         switch (opt) {
             case 'a':
@@ -467,32 +427,32 @@ int main(int argc, char **argv)
                 usage();
                 return EXIT_SUCCESS;
             default:
-                usage();
+                usage_short();
                 return EXIT_FAILURE;
         }
     }
 
     if (num_records == 0) {
         fprintf(stderr, "ERROR: Missing required parameter -n\n");
-        usage();
+        usage_short();
         return EXIT_FAILURE;
     }
     if (record_size == 0) {
         fprintf(stderr, "ERROR: Missing required parameter -s\n");
-        usage();
+        usage_short();
         return EXIT_FAILURE;
     }
 
     if (argc < optind + 1) {
         fprintf(stderr,
                 "ERROR: Output file name must be specified\n");
-        usage();
+        usage_short();
         return EXIT_FAILURE;
     }
 
     if (argc > optind + 1) {
         fprintf(stderr, "ERROR: Unexpected command-line parameters\n");
-        usage();
+        usage_short();
         return EXIT_FAILURE;
     }
 

src/xoroshiro128plus.h

@@ -0,0 +1,86 @@
+/*  Written in 2016-2018 by David Blackman and Sebastiano Vigna (vigna@acm.org)
+
+To the extent possible under law, the author has dedicated all copyright
+and related and neighboring rights to this software to the public domain
+worldwide. This software is distributed without any warranty.
+
+See <http://creativecommons.org/publicdomain/zero/1.0/>. */
+
+/*
+ * Modified by Joris van Rantwijk to fit in a C++ class.
+ */
+
+#ifndef XOROSHIRO128PLUS_H_
+#define XOROSHIRO128PLUS_H_
+
+#include <stdint.h>
+
+/* ==== Comments from the reference implementation: */
+
+/* This is xoroshiro128+ 1.0, our best and fastest small-state generator
+   for floating-point numbers, but its state space is large enough only
+   for mild parallelism. We suggest to use its upper bits for
+   floating-point generation, as it is slightly faster than
+   xoroshiro128++/xoroshiro128**. It passes all tests we are aware of
+   except for the four lower bits, which might fail linearity tests (and
+   just those), so if low linear complexity is not considered an issue (as
+   it is usually the case) it can be used to generate 64-bit outputs, too;
+   moreover, this generator has a very mild Hamming-weight dependency
+   making our test (http://prng.di.unimi.it/hwd.php) fail after 5 TB of
+   output; we believe this slight bias cannot affect any application. If
+   you are concerned, use xoroshiro128++, xoroshiro128** or xoshiro256+.
+
+   We suggest to use a sign test to extract a random Boolean value, and
+   right shifts to extract subsets of bits.
+
+   The state must be seeded so that it is not everywhere zero. If you have
+   a 64-bit seed, we suggest to seed a splitmix64 generator and use its
+   output to fill s. 
+
+   NOTE: the parameters (a=24, b=16, b=37) of this version give slightly
+   better results in our test than the 2016 version (a=55, b=14, c=36).
+*/
+
+/* ==== Modified code: */
+
+/**
+ * Pseudo random number generator "xoroshiro128+"
+ *
+ * This code is based on the reference implementation,
+ * modified by Joris van Rantwijk to fit in a C++ class.
+ *
+ * Source: http://prng.di.unimi.it/
+ */
+class Xoroshiro128plus
+{
+
+public:
+    Xoroshiro128plus(uint64_t s0, uint64_t s1)
+    {
+        m_state[0] = s0;
+        m_state[1] = s1;
+    }
+
+    inline uint64_t next()
+    {
+        const uint64_t s0 = m_state[0];
+        uint64_t s1 = m_state[1];
+        const uint64_t result = s0 + s1;
+
+        s1 ^= s0;
+        m_state[0] = rotl(s0, 24) ^ s1 ^ (s1 << 16);
+        m_state[1] = rotl(s1, 37);
+
+        return result;
+    }
+
+private:
+    static inline uint64_t rotl(uint64_t x, int k)
+    {
+        return (x << k) | (x >> (64 - k));
+    }
+
+    uint64_t m_state[2];
+};
+
+#endif  // XOROSHIRO128PLUS_H_

tests/run_tests.sh

@@ -0,0 +1,279 @@
+#!/bin/bash
+
+#
+# This script runs a series of tests on the SortBin tool.
+#
+# The tests are relatively small.
+# The whole test suite requires less than 1 GB disk space and 1 GB memory.
+#
+# This script assumes it runs from the "tests" subdirectory of the repository
+# and expects the SortBin tools already built in the "build" subdirectory.
+#
+# This script writes temporary data files to a subdirectory "testdata"
+# in the current working directory.
+#
+
+SCRIPTDIR=$(dirname "$0")
+
+# Tools under test.
+RECGEN="${SCRIPTDIR}/../build/recgen_dbg"
+SORTBIN="${SCRIPTDIR}/../build/sortbin_dbg"
+
+# GNU sort command.
+SORT="sort"
+
+# Directory for temporary test data.
+TESTDATA="testdata"
+
+
+# Run the "recgen" tool and show invocation.
+recgen () {
+    echo "${RECGEN} $*"
+    "${RECGEN}" "$@"
+}
+
+
+# Run the Unix "sort" command and show invocation.
+unixsort () {
+    echo "${SORT} --temporary-directory=${TESTDATA} $*"
+    "${SORT}" "--temporary-directory=${TESTDATA}" "$@"
+}
+
+
+# Run the "sortbin" tool and show invocation.
+sortbin () {
+    echo "${SORTBIN} --temporary-directory=${TESTDATA} --verbose $*"
+    "${SORTBIN}" "--temporary-directory=${TESTDATA}" --verbose "$@"
+}
+
+
+# Verify SHA-256 checksum.
+#   $1 = file name
+#   $2 = expected SHA-256 sum
+verify_sha256 () {
+    ( cd "${TESTDATA}" ; echo "${2}  ${1}" | sha256sum -c )
+}
+
+
+# Count number of lines in output file.
+#   $1 = output file name
+count_unique () {
+    local nline
+    nline=$(wc --lines < "${TESTDATA}/$1")
+    echo "$1: ${nline} unique records"
+}
+
+
+# Stop on the first error.
+set -e
+
+echo "Running tests"
+echo
+
+# Wipe and create test data directory, if needed.
+[ ! -d "${TESTDATA}" ] || rm -r "${TESTDATA}"
+mkdir -p "${TESTDATA}"
+
+
+#
+# Generate test input files
+#
+
+echo "Generating in01: 10 MB, 10 bytes/record, ascii, 50% duplicates"
+
+hash_in01="fe72553a046d9e268c8c9da62902f63f1ba4b02901cd2413f9f1df7792e26304"
+hash_out01="59df36e7f7895b56e59ef94cbad269cd5bec908d8a8e32aa2ca5ea624481431f"
+hash_out01u="e46e33fbf34ca575652806a51d2042b64da073d76ed52e5e74c4becb85db974f"
+
+recgen -S 1001 -s 10 -n 1000000 -a -d 0.5 "${TESTDATA}/in01"
+verify_sha256 in01 ${hash_in01}
+echo
+
+echo "Generating in02: 10 MB, 10 bytes/record, ascii, 95% duplicates"
+
+hash_in02="c5cdd3faeaf11b1a5508e3f781148a8b899514999f61917c4897bef8dc65aacf"
+hash_out02u="a95f80b2400a1e14645f1d186a065a7483c103229fc94f11bb0d62e4da6edd7d"
+
+recgen -S 1002 -s 10 -n 1000000 -a -d 0.95 "${TESTDATA}/in02"
+verify_sha256 in02 ${hash_in02}
+echo
+
+echo "Generating in03: 100 MB, 10 bytes/record, ascii, 50% duplicates"
+
+hash_in03="1a3c00a317f39e9dc336c2a46d31a3e3189a41285723f32a09be316d5273580c"
+hash_out03="f17a2e566bbccecdab04373f92ba87784af77cb36c510fb7949d7fd719528a01"
+hash_out03u="cbb975d1ce136e00668f14feb5880ebce474366ac5cb5c74287b7b4018c62b03"
+
+recgen -S 1003 -s 10 -n 10000000 -a -d 0.5 "${TESTDATA}/in03"
+verify_sha256 in03 ${hash_in03}
+echo
+
+echo "Generating in04: 100 MB, 100 bytes/record, ascii, 50% duplicates"
+
+hash_in04="75fee029fbaa762176ec4f72ecf356674dda04cefebfb01af48b17ee560f9c25"
+hash_out04u="4df05a28cdf2af29c4e8c5bb22930ee68bea12cca362ae378ab5dc6c6049fa9f"
+
+recgen -S 1004 -s 100 -n 1000000 -a -d 0.5 "${TESTDATA}/in04"
+verify_sha256 in04 ${hash_in04}
+echo
+
+echo "Generating in05: 10 MB, 10 bytes/record, binary, 50% duplicates"
+
+hash_in05="aacd9d9b1955a88397004a8ca6192b20fb9bcfa60633ac735cb6297a997f38ad"
+hash_out05u="f8b5da29076b36f7a97c9fc15da6a1754e4cc85aead368bf0540b9940f8f8cdb"
+
+recgen -S 1005 -s 10 -n 1310720 -d 0.5 "${TESTDATA}/in05"
+verify_sha256 in05 ${hash_in05}
+echo
+
+
+#
+# Run GNU sort to check reference output.
+#
+
+echo "Running GNU sort to check reference output"
+echo
+
+unixsort -o "${TESTDATA}/out01" "${TESTDATA}/in01"
+verify_sha256 out01 ${hash_out01}
+
+unixsort -o "${TESTDATA}/out01u" --unique "${TESTDATA}/in01"
+verify_sha256 out01u ${hash_out01u}
+count_unique out01u
+
+unixsort -o "${TESTDATA}/out02u" --unique "${TESTDATA}/in02"
+verify_sha256 out02u ${hash_out02u}
+count_unique out02u
+
+unixsort -o "${TESTDATA}/out03" "${TESTDATA}/in03"
+verify_sha256 out03 ${hash_out03}
+
+unixsort -o "${TESTDATA}/out03u" --unique "${TESTDATA}/in03"
+verify_sha256 out03u ${hash_out03u}
+count_unique out03u
+
+unixsort -o "${TESTDATA}/out04u" --unique "${TESTDATA}/in04"
+verify_sha256 out04u ${hash_out04u}
+count_unique out04u
+
+echo
+
+
+#
+# Test in-memory sorting.
+#
+
+echo "in01: 10 MB, in-memory sort, non-parallel, without background I/O"
+sortbin --size=10 --memory=100M --parallel=1 --no-iothread "${TESTDATA}/in01" "${TESTDATA}/out01_x"
+verify_sha256 out01_x ${hash_out01}
+rm "${TESTDATA}/out01_x"
+echo
+
+echo "in01: 10 MB, in-memory sort, non-parallel"
+sortbin --size=10 --memory=100M --parallel=1 --iothread "${TESTDATA}/in01" "${TESTDATA}/out01_x"
+verify_sha256 out01_x ${hash_out01}
+rm "${TESTDATA}/out01_x"
+echo
+
+echo "in01: 10 MB, in-memory sort, parallel"
+sortbin --size=10 --memory=100M --parallel=4 --iothread "${TESTDATA}/in01" "${TESTDATA}/out01_x"
+verify_sha256 out01_x ${hash_out01}
+rm "${TESTDATA}/out01_x"
+echo
+
+echo "in01: 10 MB, in-memory sort, unique, parallel"
+sortbin --size=10 --memory=100M --parallel=4 --iothread --unique "${TESTDATA}/in01" "${TESTDATA}/out01u_x"
+verify_sha256 out01u_x ${hash_out01u}
+rm "${TESTDATA}/out01u_x"
+echo
+
+echo "in02: 10 MB, many duplicates, in-memory sort, unique, parallel"
+sortbin --size=10 --memory=100M --parallel=4 --iothread --unique "${TESTDATA}/in02" "${TESTDATA}/out02u_x"
+verify_sha256 out02u_x ${hash_out02u}
+rm "${TESTDATA}/out02u_x"
+echo
+
+echo "in03: 100 MB, in-memory sort, unique, parallel"
+sortbin --size=10 --memory=100M --parallel=4 --iothread --unique "${TESTDATA}/in03" "${TESTDATA}/out03u_x"
+verify_sha256 out03u_x ${hash_out03u}
+rm "${TESTDATA}/out03u_x"
+echo
+
+echo "in04: 100 MB, big records, in-memory sort, unique, parallel"
+sortbin --size=100 --memory=100M --parallel=4 --iothread --unique "${TESTDATA}/in04" "${TESTDATA}/out04u_x"
+verify_sha256 out04u_x ${hash_out04u}
+rm "${TESTDATA}/out04u_x"
+echo
+
+echo "in05: 10 MB, binary data, in-memory sort, unique, parallel"
+sortbin --size=10 --memory=100M --parallel=4 --iothread --unique "${TESTDATA}/in05" "${TESTDATA}/out05u_x"
+verify_sha256 out05u_x ${hash_out05u}
+rm "${TESTDATA}/out05u_x"
+echo
+
+
+#
+# Test external sorting.
+#
+
+echo "in03: 100 MB, external sort, 1 merge pass"
+sortbin --size=10 --memory=20M --parallel=4 --iothread "${TESTDATA}/in03" "${TESTDATA}/out03_x"
+verify_sha256 out03_x ${hash_out03}
+rm "${TESTDATA}/out03_x"
+echo
+
+echo "in03: 100 MB, external sort, 1 merge pass, unique"
+sortbin --size=10 --memory=20M --parallel=4 --iothread --unique "${TESTDATA}/in03" "${TESTDATA}/out03u_x"
+verify_sha256 out03u_x ${hash_out03u}
+rm "${TESTDATA}/out03u_x"
+echo
+
+echo "in05: 10 MB, binary data, external sort, 1 merge pass, equal block sizes"
+sortbin --size=10 --memory=5M --parallel=4 --iothread --unique "${TESTDATA}/in05" "${TESTDATA}/out05u_x"
+verify_sha256 out05u_x ${hash_out05u}
+rm "${TESTDATA}/out05u_x"
+echo
+
+echo "in03: 100 MB, external sort, 2 merge passes, unique, without background I/O"
+sortbin --size=10 --memory=10M --parallel=4 --no-iothread --branch=4 --unique "${TESTDATA}/in03" "${TESTDATA}/out03u_x"
+verify_sha256 out03u_x ${hash_out03u}
+rm "${TESTDATA}/out03u_x"
+echo
+
+echo "in03: 100 MB, external sort, 2 merge passes, unique"
+sortbin --size=10 --memory=20M --parallel=4 --iothread --branch=4 --unique "${TESTDATA}/in03" "${TESTDATA}/out03u_x"
+verify_sha256 out03u_x ${hash_out03u}
+rm "${TESTDATA}/out03u_x"
+echo
+
+echo "in03: 100 MB, external sort, 2 merge passes, balanced merge tree"
+sortbin --size=10 --memory=22M --parallel=4 --iothread --branch=3 "${TESTDATA}/in03" "${TESTDATA}/out03_x"
+verify_sha256 out03_x ${hash_out03}
+rm "${TESTDATA}/out03_x"
+echo
+
+echo "in03: 100 MB, external sort, 2 merge passes, slightly unbalanced merge"
+sortbin --size=10 --memory=20M --parallel=4 --iothread --branch=9 "${TESTDATA}/in03" "${TESTDATA}/out03_x"
+verify_sha256 out03_x ${hash_out03}
+rm "${TESTDATA}/out03_x"
+echo
+
+echo "in03: 100 MB, external sort, 2 merge passes, slightly unbalanced merge"
+sortbin --size=10 --memory=13M --parallel=4 --iothread --branch=4 "${TESTDATA}/in03" "${TESTDATA}/out03_x"
+verify_sha256 out03_x ${hash_out03}
+rm "${TESTDATA}/out03_x"
+echo
+
+echo "in03: 100 MB, external sort, 2-way merging, 5 merge passes"
+sortbin --size=10 --memory=10M --parallel=4 --iothread --branch=2 "${TESTDATA}/in03" "${TESTDATA}/out03_x"
+verify_sha256 out03_x ${hash_out03}
+rm "${TESTDATA}/out03_x"
+echo
+
+echo "in03: 100 MB, external sort, 24-way merge, 1 merge pass"
+sortbin --size=10 --memory=8M --parallel=4 --iothread --branch=24 "${TESTDATA}/in03" "${TESTDATA}/out03_x"
+verify_sha256 out03_x ${hash_out03}
+rm "${TESTDATA}/out03_x"
+echo
+
+echo "Tests finished"