add HISTSIZE for readline to limit the number of cached commands

doc/src/sgml/ref/psql-ref.sgmlin

@@ -2833,6 +2833,22 @@ bar
         </listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><varname>HISTSIZE</varname></term>
+        <listitem>
+        <para>
+        The number of commands to store in the command history. The
+        default value is 500.
+        </para>
+        <note>
+        <para>
+        This feature was shamelessly plagiarized from
+        <application>Bash</application>.
+        </para>
+        </note>
+        </listitem>
+      </varlistentry>
+
       <varlistentry>
         <term><varname>HOST</varname></term>
         <listitem>

src/bin/psql/command.cpp

@@ -1051,6 +1051,12 @@ static backslashResult exec_command(const char* cmd, PsqlScanState scan_state, P
                 success = false;
             }
 
+#ifdef USE_READLINE
+            if (useReadline && pset.cur_cmd_interactive) {
+                setHistSize(opt0, newval, false);
+            }
+#endif
+
             free(newval);
             newval = NULL;
             if (temp_opt != NULL)
@@ -1255,6 +1261,12 @@ static backslashResult exec_command(const char* cmd, PsqlScanState scan_state, P
             success = false;
         }
 
+#ifdef USE_READLINE
+        if (useReadline && pset.cur_cmd_interactive) {
+            setHistSize(opt, NULL, true);
+        }
+#endif
+
         if (NULL != opt) {
             free(opt);
             opt = NULL;

src/bin/psql/input.cpp

@@ -248,6 +248,45 @@ bool SensitiveStrCheck(const char* target)
     }
 }
 
+void setHistSize(const char* targetName, const char* targetValue, bool setToDefault)
+{
+#ifndef ENABLE_LLT
+    char* end = NULL;
+    long int result;
+#define MAXHISTSIZE 500
+#define DEFHISTSIZE 32
+    if (targetName == NULL) {
+        return;
+    }
+    if (strcmp(targetName, "HISTSIZE") == 0) {
+        if (!setToDefault) {
+            if (targetValue == NULL || strlen(targetValue) == 0) {
+                fprintf(stderr, "warning:\"HISTSIZE\" is not changed,because its value can not be null\n");
+                return;
+            } else {
+                errno = 0;
+                result = strtol(targetValue, &end, 0);
+                if ((errno == ERANGE && (result == LONG_MAX || result == LONG_MIN)) || (errno != 0 && result == 0)) {
+                    fprintf(stderr, "warning:\"HISTSIZE\" is not changed,because its value overflows\n");
+                    return;
+                }
+                if (*end || result < 0) {
+                    fprintf(stderr, "warning:\"HISTSIZE\" is not changed,because its value must be positive integer\n");
+                    return;
+                }
+            }
+            if (result > MAXHISTSIZE) {
+                fprintf(stderr, "warning:\"HISTSIZE\" is set to 500,because its value can not be greater than 500\n");
+                result = MAXHISTSIZE;
+            }
+        } else {
+            result = DEFHISTSIZE;
+        }
+        stifle_history((int)result);
+    }
+#endif
+}
+
 /*
  * Put any startup stuff related to input in here. It's good to maintain
  * abstraction this way.

src/bin/psql/input.h

@@ -8,7 +8,6 @@
 #ifndef INPUT_H
 #define INPUT_H
 
-#ifdef HAVE_LIBREADLINE
 /*
  * If some other file needs to have access to readline/history, include this
  * file and save yourself all this work.
@@ -17,6 +16,8 @@
  */
 #define USE_READLINE 1
 
+#ifdef HAVE_LIBREADLINE
+
 #if defined(HAVE_READLINE_READLINE_H)
 #include <readline/readline.h>
 #include <readline/history.h>
@@ -36,6 +37,7 @@ char* gets_fromFile(FILE* source);
 
 void pg_append_history(const char* s, PQExpBuffer history_buf);
 void pg_send_history(PQExpBuffer history_buf);
+void setHistSize(const char* targetName, const char* targetValue, bool setToDefault);
 extern bool useReadline;
 extern bool SensitiveStrCheck(const char* target);
 

src/bin/psql/mainloop.cpp

@@ -148,6 +148,11 @@ int MainLoop(FILE* source, char* querystring)
     }
     pset.lineno = 0;
 
+    if (pset.cur_cmd_interactive) {
+        const char* val = GetVariable(pset.vars, "HISTSIZE");
+        setHistSize("HISTSIZE", val, val == NULL);
+    }
+
     /* Create working state */
     scan_state = psql_scan_create();
 

src/bin/psql/startup.cpp

@@ -781,6 +781,7 @@ static void parse_psql_options(int argc, char* const argv[], struct adhoc_opts*
                         fprintf(stderr, _("%s: could not set variable \"%s\"\n"), pset.progname, value);
                         exit(EXIT_FAILURE);
                     }
+                    setHistSize(value, equal_loc + 1, false);
                 }
 
                 free(value);

src/bin/psql/tab-complete.cpp

@@ -754,8 +754,12 @@ void initialize_readline(void)
 {
     rl_readline_name = (char *)pset.progname;
 
+#ifdef HAVE_READLINE_READLINE_H
     /* PsqlCompletion is deleted because it's too complex and not be used at all. */
     rl_attempted_completion_function = PsqlCompletion;
+#else
+    rl_attempted_completion_function = NULL;
+#endif
 
     rl_basic_word_break_characters = WORD_BREAKS;
 

src/test/regress/expected/readline.out

@@ -7,3 +7,11 @@ select * from 数据库;
  1
 (1 row)
 
+\set HISTSIZE -1
+\set HISTSIZE 30.5
+\set HISTSIZE 0
+\set HISTSIZE 6
+\set HISTSIZE 500
+\set HISTSIZE 600
+\set HISTSIZE 66666666666666666666666600
+\set HISTSIZE -666666666666666666666666666

src/test/regress/sql/readline.sql

@@ -2,3 +2,11 @@
 create table 数据库(f int);
 insert into 数据库 values (1);
 select * from 数据库;
+\set HISTSIZE -1
+\set HISTSIZE 30.5
+\set HISTSIZE 0
+\set HISTSIZE 6
+\set HISTSIZE 500
+\set HISTSIZE 600
+\set HISTSIZE 66666666666666666666666600
+\set HISTSIZE -666666666666666666666666666